(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY(PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`
`
`AQUAAA
`
`(10) International Publication Number
`(43) International Publication Date
`WO 01/65786 Al
`7 September 2001 (07.09.2001)
`PCT
`
`
`(51) International Patent Classification’:
`12/43, HO4J 3/02, HO4L 1/00
`
`HO4L 12/66,
`
`(21) International Application Number:
`
`PCT/US00/28386
`
`(22) International Filing Date: 13 October 2000 (13.10.2000)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(72) Inventors: EREKSON, Rich; 4760 South 3350 West,
`Roy, UT 84067 (US). ALDRIDGE, Timothy, W.; 939 East
`Edgefield Road, Sandy, UT 84094 (US). PRICE, Tim, U.;
`568 East Water Lily Drive, Salt Lake City, UT 84106 (US).
`
`(74) Agents: MASCHOFF, Eric,L. et al.; Workman, Nydeg-
`ger & Seeley, 1000 Eagle Gate Tower, 60 East South Tem-
`ple, Salt Lake City, UT 84111 (US).
`
`(81) Designated State (national): JP.
`
`Published:
`
`(30) Priority Data:
`09/5 16,857
`
`2 March 2000 (02.03.2000)
`
`US
`
`with international search report
`
`(71) Applicant: 3COM CORPORATION [US/US]; 5400
`Bayfront Plaza, Santa Clara, CA 95052-8145 (US).
`
`For two-letter codes and other abbreviations, refer to the "Guid-
`ance Notes on Codes and Abbreviations" appearing at the begin-
`ning ofeach regular issue of the PCT Gazette.
`
`
`
`(54) Title: VOICE-OVER-IP INTERFACE FOR STANDARD HOUSEHOLD TELEPHONE
`
`
`
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`(57) Abstract: The presentinvention enablesa traditional analog telephone (Fig. 1) to be used with VoIP applications. For example,
`the user should connecttheir standard 900 MHz telephoneto this invention, establish a VoIP call and enjoy the freedom of movement
`their cordless telephone provides. The preferred embodimentof the present invention minimizes overhead to the host computer via
`a dual CODEC modem that incorporates a DSP (610) capable of simultaneous communication with the two CODEC modules. This
`architecture facilitates a latency and communication overhead reduction as the analog voice signals effectively "stream" from the
`first CODEC (620) to the second CODEC(630).
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`VOICE-OVER-IP INTERFACE FOR STANDARD HOUSEHOLD TELEPHONE
`
`BACKGROUND OF THE INVENTION
`
`1.
`
`The Field of the Invention
`
`This
`
`invention is
`
`in the field of Voice Over
`
`Internet Protocol
`
`(VoIP)
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`communications and, moreparticularly, to a system and methodofinterfacing a standard
`
`telephone to a VoIP compatible communication network.
`
`2.
`
`The Prior State of the Art
`
`Voice Over Internet Protocol (VoIP) is an emerging technology that allows the
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`systems and wires that connect computer networksto act as an alternative to phone lines,
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`delivering real-time voice to both standard telephones and PCs. VoIP allows an
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`individual
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`to utilize their computer connection to transmit voice encapsulated data
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`packets over available local communicationlines, such as the Internet, to another user on
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`another computer, thereby creating a long distance phonecall at a local connection price.
`
`How VoIP works
`
`In a Voice-over-IP (VoIP) system, the analog voice signalis typically picked up
`
`by a microphone and sent to an audio processor within a PC. There, either a software or
`
`hardware CODECperformsanalog-to-digital conversion and compression. Considerable
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`research has been devoted to voice compression schemes that are well know to those
`
`skilled in the art. The nominal bandwidth required for telephone-type voice ranges from
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`20
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`2.9 Kbps (RT24 by Voxware) to 13 Kbps (GSM cellular standard).
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`In placing the CODEC output
`
`into packets,
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`there is a trade-off between
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`bandwidth and latency. CODECs do not operate continuously. Instead, they sample the
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`voice over a short period of time, known as a frame. These framesare likelittle bursts of
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`data. One or more frames can be placed in a single IP datagram or packet, and then the
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`packet payload is wrapped in the necessary packet headers andtrailers. This packet
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`overheadis at least 20 bytes for IP and 8 bytes for the User Datagram Protocol (UDP).
`Layer 2 protocols add even more overhead. Waiting longer to fill
`the IP datagram
`reduces overall overhead, which in tum reducesthe true bandwidth needed to send the
`digitized voice. However, this waiting creates latency at the source, and too muchtotal
`latency makesfor a difficult conversation. Chart 1 showsthe basic trade-off for initial
`
`latency versus true bandwidth.
`200
`
`
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`Initiatsourcelatency(msec)
`
`
`
`
`
`8ree
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`0
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`20
`.
`10
`True bandwidth needed (Kbps)
`Chart 1. Latency vs. Bandwidth Requiredfor Voice-over-IP
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`30
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`The total network latency andjitter (changes in the latency) have a degrading
`
`effect upon voice quality. Therefore, real-time voice quality is difficult to maintain over
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`a large wide-area packet network withoutpriority handling. As previously mentioned,
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`VoIP converts standard telephone voice signals into compressed data packets that can be
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`sent locally over Ethemet or globally via an ISP's data networks rather than traditional
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`phone lines. One of the main difficulties with VoIP connections
`
`is
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`that
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`the
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`communication network supporting a VoIP platform mustbe ableto recognize that VoIP
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`data packets contain voice signals, and be
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`"smart"
`
`enough to know that
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`the
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`communication network has to move the data packets quickly.
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`Presently, serious voice traffic does not use the public Internet but runs on private
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`IP-based global networksthat can deliver voice data with minimal congestion. As such,
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`transmission of voice signals over private data networks offers businesses some great
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`advantages. For ISPs, merging voice and data on one single network allows them to
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`expand their services beyond simple information access andinto the realm of voice, fax,
`
`and virtual private networking. For businesses,
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`the benefit is big savings on long-
`
`distance service. The Internet right now is a free medium on many networks. If
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`businesses can send voice over a computer network, businesses can conceivably make
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`long-distance or international calls for the cost of a local call. VoIP further facilitates
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`electronic commerce by allowing a customer service rep using one data line to answer
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`telephone questions while simultaneously placing a customer’s order online, perusing the
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`company's website, browsing an online information/product database, or sending an E-
`
`mail. Similarly, VoIP also creates new possibilities for remote workers, who for the cost
`
`of a local call can log in remotely, retrieve voice mail from their laptop PCs, and keep
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`their E-mail and web applications running while conducting multiple voice anddata calls
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`over one phone line. Presently, this type of expanded VoIP functionality is exclusively
`
`limited to those with accessto private IP based networks, such as business users and not
`
`the typical household user.
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`In fact, most household computer users are generally limited to the congested
`
`public Internet and cannot implement the VoIP standard effectively. If latency andjitter
`
`are too high, or the cost of reducing them is excessive, one alternative is to buffer the
`
`CODEC data at the receiver. A large buffer can be filled irregularly but emptied at a
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`20
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`uniform rate. This permits good quality reproduction of voice. Such a buffering
`
`technique is known as audio streaming, andit is a very practical approach for recorded
`
`voice or audio. Unfortunately, excessive buffering of the audiosignals leads to generally
`
`unacceptable one-sided telephone conversations, where one party dominates
`
`the
`
`transmissions. What
`
`is needed is a packetized telephone system that
`
`is able to
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`compensateforlatency andjitter, without introducing noticeable buffering.
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`Traditionally,
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`the operating environment for a household user with a VoIP
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`connection is either a laptop or desktop general-purpose computer. The recording and
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`transmission or interpretation of the VoIP packets takes place in the sound system or
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`modem DSP found on the laptop or desktop. As such, the desktop system has a minor
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`advantage over the laptop, because the desktop sound system traditionally provides
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`stereo surround speakers and an accurate microphone. Thus, the desktop system can
`
`more accurately capture an individual’s voice for retransmission of these voice signals to
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`the user on the other end of the connection. VoIP telephone software buffering and
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`control structures help improve the connection, but even though the audio signal has
`
`been accurately sampled, the processor delays and transmission latency associated with
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`the desktop VoIP connection over the public Internet tends to result in a barely audible
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`VoIP call. What is needed is a household compatible packetized telephone system thatis
`
`able to compensate for communication network delays and hardware limitations, without
`
`introducing noticeable degradation into the voice signal.
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`One of the main difficulties with using VoIP in a household system is that the
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`protocol requires the user to follow numerous steps in order to establish a voice
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`connection.
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`In addition to the normal boot-up process associated with general-purpose
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`computers for the operating system and the Internet telephone application, there are
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`several details difficult for the household user to provide. For example, if a user were
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`20
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`trying to contact anotherindividual, they would need to know the individual’s IP address
`
`and punch the address into their software application or web browser to contact the
`
`individual. Once the user contacts the individual through either E-mail or at the website,
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`the user must notify them that the user wishes to initiate a VoIP connection. Then the
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`individual being contacted would enable their VoIP to allow the user to begin streaming
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`25
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`voice packets between the two devices. What is needed is a simple method of using
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`VoIP with a household telephone, so that at the time the call is placed a user need only
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`dial the access number on the telephone for the VoIP connection to be initiated and if
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`possible connected.
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`In addition to the start-up delay and the awkward communication setup for most
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`desktop systems, another problem with present VoIP systems
`
`is
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`the immobility
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`limitations imposed on the user by the VoIP desktop system. While the sound system is
`
`able to make an accurate recording, the user mustsit at the desktop location or at least
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`within range of the attached microphones and speakers to communicate. Unlike a
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`telephone,
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`the desktop system is very difficult to move to another room andit is
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`generally considered very impractical to have multiple Internet capable workstationsin
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`one house dueto the cost for each workstation. In effect, the user is “chained” to the one
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`location and the problems associated with talking over the computer sound system
`
`whenever the user desires to make VoIP calls. What is needed is a simple method of
`
`integrating a typical cordless phone with a computer to obtain a short-range wireless
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`15
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`VoIP connection with the look and feel of a standard household telephone system.
`
`Being mobile by nature, laptop sound systems present a different problem. As
`
`these systems are generally a design afterthought, it is often challenging for the user to
`
`even turn on the microphone,let alone conduct a VoIP session. The laptop microphone
`
`is generally very small, inexpensive, and mounted inconspicuously on the laptop case
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`20
`
`makingit difficult for the microphone to function at quality levels comparable to what
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`users have come to expect from a telephone. Thus, one of the problems facing VoIP is
`
`that home users are used to talking on telephones and expect a certain quality of sound in
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`communication between them and another user. What
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`is needed is a method of
`
`integrating VoIP communication that also removes the limitations presently associated
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`with computer-based speakerphones.
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`SUMMARY OF THE INVENTION
`
`Accordingly, one advantage of the inventionis to create the samelook,feel, and
`
`usage to which the user is accustomed from the standard telephone connection.
`
`Another advantage of the invention is to provide a method and system that
`
`facilitates short-range wireless telephone functionality between a handset and a base
`
`station, while maintaining VoIP communication between a dialed party and a host
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`computerattachedto the short-range wirelessbasestation.
`
`A further advantage of the invention is to provide a packetized telephone system
`
`that is able to compensate for latency andjitter, without introducing noticeable buffering
`
`delays.
`
`It is another advantage of the present invention to provide a system that integrates
`
`a cordless telephone with a host computer system to thereby release the requirementthat
`
`the user placing a VoIPcall be in the nearvicinity of the connection origin.
`
`Yet another advantage of the invention is transmission of various digitally
`
`reproduced audio signals to the telephone headset indicating the status of the VoIP
`
`telephone application, wherein the audio signals closely resemble the error and status
`
`signals present on the standard telephone system.
`
`The above and other advantages of the invention are satisfied at least in part by
`
`providing interface circuitry and software on or between a short-range wireless telephone
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`20
`
`and a host computer. The interface analyzes and converts analog voice signals from the
`
`telephone handset microphone into digital packets for transmission according to a VoIP
`
`protocol across an attached communication network. Received digital packets are
`
`converted by the interface into an analog signal for transmission by the telephone
`
`handset speaker. The circuitry comprises a podule and a dual CODEC modem. The
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`podule is capable of generating voltage for ring signals, dial tones, busy signals, and
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`error codes to the headset according to inputs from the attached modem DSP. The
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`podule also converts the two-wire telephone connection into a four-wire connection and
`
`imitates the isolation barrier responses of POTS. The dual CODEC modemis capable of
`
`converting voice and data transmissions through the first CODEC pipeline and
`
`transceiving encapsulated data packets received or sent via the attached communication
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`network through the second CODEC pipeline.
`
`The modem DSP is capable of
`
`simultaneously maintaining sessions with both CODECs. The software and modem DSP
`
`work in conjunction to generate various logical control signals for the VoIP interface and
`
`control communication across the interface circuitry.
`
`The software and circuitry
`
`interface being able to generate a ring signal in the attached telephone handset after
`
`detecting an incoming VoIPcall. The interface also generating error tones and dial tones
`
`whenthe software application is running and the handsetis off-hook.
`
`In addition to the improvedarchitectutre of the dual CODEC modem,the present
`
`invention also benefits from the improved network connections available to the
`
`household user, such as G-lite DSL, aDSL, or xDSL network connections. While a user
`
`can use a standard telephone, plug it into the present invention, and make VoIPcalls,
`
`through the standard PSTN or POTS connection, the more preferred network connection
`
`is a sub-rate DSL connection. A G-lite DSL connection is a sub-rate of a Digital
`
`Subscriber Link (DSL).
`
`If a full rate DSL connection has a 10 Megabyte bandwidth, a
`
`G-lite DSL user could order a portion of that bandwidth and be able to avoid the cost of
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`20
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`the full bandwidth. For the average user, a 1.5 Megabyte bandwidth would be sufficient
`
`to transmit and receive voice packets at a rate at which the user would not notice a
`
`difference in sound between a telephone connection and an Internet connection.
`
`In
`
`essence, the G-lite DSL connection enables a user to use a sub-rated DSL to obtain the
`
`VoIP performance necessary for a comparison phoneline connection. In this manner, the
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`25
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`present invention facilitates household users of VoIP talking from PC-to-PC, phone-to-
`
`phone, or even PC-to-phone.
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`The present invention allows a VoIP household user to pick up an attached
`
`telephone and dial the appropriate DTMFdigits, which are intercepted by the modem.
`
`The modem references the detected digits in a database or look-up file containing pre-set
`
`values that correlate the dialed number to an IP address. If a value is discovered the
`
`present invention will attempt to initiate the VoIP connection.
`
`In essence, this process
`
`enables a user to selectively establish a telephone communication methodutilizing the
`
`most inexpensive method of connection. For example if a VoIP connection is available
`
`for a long distance call, the phone interface will automatically select and contactthat
`
`type of connection. But if a standard connection is required, then the phone will utilize
`
`attached PSTN linesto establish a standard phone connection.
`
`As previously mentioned, a significant advantage of this invention is the
`
`enhancedutilization of a processor which has two separate CODEC modules on board
`
`allowing a user to run two CODECsessions. For example, one device has a CODEC for
`
`a cell phone and another for an analog line or PSTN connection. This processor can
`
`easily be modified such that an individual may use one CODEC for data through the
`
`telephone and communicate back and forth to the telephone using that CODEC, while
`
`the other CODECisutilized with either a G-lite connection or across the standard PSTN
`
`phone line. While this particular invention would work over the modem protocol
`
`standard V.90, the preferred embodimentutilizes G._lite.
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`20
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`Additional objects and advantages of the invention will be set forth in the
`
`description which follows, and in part will be obvious from the description, or may be
`
`learned by the practice of the invention. The objects and advantages of the invention
`
`may berealized and obtained by meansof the instruments and combinationsparticularly
`
`pointed out in the appended claims. These and other objects and features of the present
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`25
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`invention will become more fully apparent from the following description and appended
`
`claims, or may be learned bythepractice ofthe invention as set forth hereinafter.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`In order that the manner in which the above recited and other advantages and
`
`objects of the invention are obtained, a more particular description of the invention
`
`briefly described above will be rendered by reference to specific embodiments thereof
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`5
`
`whichareillustrated in the appended drawings. Understanding that these drawing depict
`
`only typical embodiments of the invention and are not therefore to be considered to be
`
`limiting of its scope,
`
`the invention will be described and explained with additional
`
`specificity and detail through the use of the accompanying drawingsin which:
`
`Figure 1
`
`illustrates an exemplary system that provides a suitable operating
`
`10.
`
`environmentfor the present invention;
`
`Figure 2 illustrates another exemplary system that provides a podule interface
`
`connection between a household telephone and a laptop computer,
`
`Figure 3 is a block diagram of a suitable dual CODEC modem useful for the
`
`present invention;
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`15
`
`Figure 4 is a schematic illustration of a podule interface for use with the present
`
`invention;
`
`Figure 5 is a flow chart of a VoIPcall using the VoIP interface; and
`
`Figure 6 is a computerless exemplary system that provides a podule interface
`
`betweena short-range wireless telephone and a communication network.
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`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`The invention is described below using diagramsto illustrate either the structure
`
`or the processing of embodiments used to implement the systems and methods of the
`
`present invention. Using the diagramsin this mannerto present the invention should not
`
`be construed as limiting of its scope. The present invention contemplates both methods
`
`and systems for Voice-over-Internet-Protocol interfacing and communication between a
`
`standard household short-range wireless telephone (e.g. a 900MHz, Bluetooth, 802.11
`
`RF interface or other wireless interface) and a PC. The embodiments of the present
`
`invention may comprise a special purpose or general-purpose computer including
`
`various computer hardwareconfigurations, as discussed in greater detail below.
`
`Embodiments within the scope of the present invention also include computer-
`
`readable media for carrying or having computer-executable instructionsor data structures
`
`stored thereon. Such computer-readable media can be any available media that can be
`
`accessed by a general purpose orspecial purpose computer. By way of example, and not
`
`limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-
`
`ROM or other optical disk storage, magnetic disk storage or other magnetic storage
`
`devices, or any other medium which can beusedto carry or store desired program code
`
`meansin the form of computer-executable instructions or data structures and which can
`
`be accessed by a general purpose or special purpose computer. When information is
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`20
`
`transferred or provided over a network or another communications connection (either
`
`hardwired, wireless, or a combination of hardwired or wireless) to a computer, the
`
`computer properly views the connection as a computer-readable medium. Thus, any
`
`such connection is properly termed a computer-readable medium. Combinationsofthe
`
`above should also be included within the scope of computer-readable media. Computer-
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`be
`
`executable instructions comprise, for example,
`
`instructions and data which cause a
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`general purpose computer, special purpose computer, or special purpose processing
`
`device to perform a certain function or group offunctions.
`
`Figure 1 and the following discussion are intended to provide a brief, general
`
`description of a suitable computing environment
`
`in which the invention may be
`
`implemented. The invention will be described in the general context of computer-
`
`executable instructions, such as program modules, being executed by computers in
`
`network environments. Generally, program modules include routines, programs, objects,
`
`components, data structures, etc. that perform particular tasks or implementparticular
`
`abstract data types. Computer-executable instructions, associated data structures, and
`
`program modules represent examples of the program code means for executing steps of
`
`the methods disclosed herein. The particular sequences of such executable instructions
`
`or associated data structures represent examples of corresponding acts for implementing
`
`the functions described in such steps.
`
`Those skilled in the art will appreciate that the invention may bepracticed in
`
`network computing environments with many types of computer system configurations,
`
`including
`
`personal
`
`computers,
`
`hand-held
`
`devices, multi-processor
`
`systems,
`
`microprocessor-based
`
`or
`
`programmable
`
`consumer
`
`electronics,
`
`network
`
`PCs,
`
`minicomputers, mainframe computers, Personal Digital Assistants, and the like. The
`
`invention may also be practiced in distributed computing environments where local and
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`20
`
`remote processing devices perform tasks that are linked (either by hardwired links,
`
`wireless links, or by a combination of hardwired or wireless links)
`
`through a
`
`communications network.
`
`In a distributed computing environment, program modules
`
`may be located in both local and remote memory storage devices.
`
`With reference to Figure 1, an exemplary system for implementing the invention
`
`25
`
`includes a general-purpose computing device in the form of a conventional computer 20,
`
`including a processing unit 21, a system memory 22, and a system bus 23 that couples
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`various system components including the system memory 22 to the processing unit 21.
`
`The system bus 23 maybeanyofseveral types of bus structures including a memory bus
`
`or memory controller, a peripheral bus, and a local bus using any of a variety of bus
`
`architectures. The system memory includes read only memory (ROM) 24 and random
`
`access memory (RAM) 25.Abasic input/output system (BIOS) 26, containing the basic
`
`routines that help transfer information between elements within the computer 20, such as
`
`duringstart-up, may be stored in ROM 24.
`
`The computer 20 may also include a magnetic hard disk drive 27 for reading
`
`from and writing to a magnetic hard disk 39, a magnetic disk drive 28 for reading from
`
`or writing to a removable magnetic disk 29, and anoptical disk drive 30 for reading from
`
`or writing to removable optical disk 31 such as a CD-ROM orother optical media. The
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`magnetic hard disk drive 27, magnetic disk drive 28, and optical disk drive 30 are
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`connected to the system bus 23 by a hard disk drive interface 32, a magnetic disk drive-
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`interface 33, and an optical drive interface 34, respectively. The drives and their
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`associated computer-readable media provide nonvolatile storage of computer-executable
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`instructions, data structures, program modules and other data for the computer 20.
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`Although the exemplary environment described herein employs a magnetic hard disk 39,
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`a removable magnetic disk 29 and a removable optical disk 31, other types of computer
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`readable media for storing data can be used, including magnetic cassettes, flash memory
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`20
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`cards, digital video disks, Bernoulli cartridges, magnetic tapes, RAMs, ROMs, and the
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`like.
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`Program code means comprising one or more program modules maybe stored on
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`the hard disk 39, magnetic disk 29, optical disk 31, ROM 24 or RAM 25, including an
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`operating system 35, one or more application programs 36, other program modules 37,
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`25
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`and program data 38. A user may enter commandsand information into the computer 20
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`through keyboard 40, pointing device 42, PDA cradle 56, or other input devices (not
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`shown), such as a microphone, joy stick, game pad, digital camera, satellite dish,
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`scanner, or the like. These and other input devices are often connected to the processing
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`unit 21 through a serial port interface 46 coupled to system bus 23. Alternatively, the
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`input devices may be connected by other interfaces, such as a parallel port, a serial port,
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`an infra-red port, a short-range wireless port, an RF port, or a game port or a universal
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`serial bus (USB). A short range wireless telephone handset 66 or another short-range
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`wireless (e.g. 900 MHz, Bluetooth, 802.11 RF or other wireless interface) enabled device
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`is connected to the system bus 23 via antenna 60 attached to short-range wireless base
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`station transceiver 64 that is connected to sound system interface 58. Alternatively, the
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`short-range wireless base station 64 may be connected to computer 20 via other
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`interfaces, such as a modem interface, a podule interface, peripheral port interface 46, or
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`other telephone compatible interface capable of receiving and converting audio signals
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`into data packets and for converting and transmitting digital packets into audio signals.
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`A monitor 47 or another display device is also connected to system bus 23 via an
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`interface, such as video adapter 48.
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`In addition to the monitor, personal computers
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`typically include other peripheral output devices (not shown), such as speakers and
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`printers.
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`The computer 20 may operate in a networked environment using logical
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`connections to one or more remote computers, such as remote computers 49a and 49b.
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`20
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`Remote computers 49a and 49b may each be another personal computer, a server, a
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`router, a network PC, a PDA, a peer device or other common network node, and
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`typically includes manyorall of the elements described aboverelative to the computer
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`20, although only memory storage devices 50a and 50b andtheir associated application
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`programs 36a and 36b have been illustrated in Figure 1.
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`The logical connections
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`23
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`depicted in Figure 1 include a local area network (LAN) 51, a local short-range wireless
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`network 62, and a wide area network (WAN) 52 that are presented here by way of
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`example and notlimitation. Multiple area network 57 is a logical connection or bridge
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`between the LAN and WANresources accessible via network interface 53 or modem 54.
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`Such networking environments are or will be commonplacein office-wide or enterprise-
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`wide computer networks, intranets andthe Internet.
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`Whenused in a LAN networking environment, the computer 20 is connected to
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`the local area network 51 through a network interface or adapter 53. When used in a
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`WAN networking environment, the computer 20 may include a modem 54, a wireless
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`link, or other means for establishing communications over the wide area network 52,
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`suchas the Internetor private IP based network. The modem 54, which maybeinternal
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`or external, is connected to the system bus 23 via the peripheral port interface 46. The
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`short-range wireless basestation transceiver 64 typically exhibits a range dependent on
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`the primary transmission protocol. For example, a device using the Bluetooth protocol
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`typically exhibits a range of approximately 10 to 30 meters, butit is anticipated that this
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`range may expand to over 30 meters. Other protocols exhibit larger operational ranges
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`for example a 900 MHz phone mayoperate at distances over one mile away. A short-
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`range wireless protocol, such as the Bluetooth protocol mayalso dictate that the number
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`of remote short-range wireless devices in communication with short-range wireless base
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`station transceiver 64 via antenna 60 at any one time, be limited to eight devices,
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`however; timeslicing and other software semaphore methods could expand the numberof
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`20
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`devices attached to the eight short-range wireless connections.
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`In a networked
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`environment, program modules depicted relative to the computer 20, or portions thereof,
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`may be stored in the remote memory storage device.
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`It will be appreciated that the
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`network connections
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`shown are
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`exemplary and other means of establishing
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`communications over wide area network 52 maybeused.
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`25
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`With reference to Figure 2, an exemplary system illustrating the podule interface
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`circuitry between an analog or standard telephone, and a computer and communication
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`environment necessary to simulate a central office that allows VoIP via a typical
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`telephone device. The telephone device may be a cordless phone, fax machine, modem,
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`etc. Although othercircuit implementations can be used, for example, a subscriber loop
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`interface or a basic ASIC,this figure illustrates the necessary functionality to accomplish
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`the communication.
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`The apparatus consists of a podule, which, on one end, allows a standard RJ11
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`cable to be connected to a standard telephone base station. The podule would be
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`powered by an AC adaptor power supply 150. The other end of podule 110 would
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`connectvia line 160 through the 15 pin connector on a modem PCcard tothe laptop 120.
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`The podule performsthe following: 1) Provides sufficient voltage and current to charge
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`the telephone’s hold circuit, 2) Capable of supplying sufficient voltage uponinitiation by
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`a control string for off-hook and ring conditions, 3) Provides a 2-4 wire conversion
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`between the podule 110 and modem of laptop 120, 4) Provides coupling circuitry
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`allowing the desired signal
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`to be passed through the podule (both RX/TX) while
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`providingthe electrical isolation required.
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`The laptop 120 has two CODECs and a DSP capable of running both CODECs
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`simultaneously. The DSP uses one of the CODECs to maintain a connection to the
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`external communication network, such as an Internet connection via a PSTN connection.
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`The other CODECis used to interface to the standard household telephone. While the
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`20
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`preferred method