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`(cid:127) another Operator who has a roaming agreement with their GSM Operator.
`
`Although these user/network scenarios focus on roaming from GSM Network Operator's network(s),
`clearly roaming can be bi-directional, i.e. from Public WLAN Operators to GSM Networks. Traditional
`roaming in networks of the same standard, e.g. from a WLAN to a WLAN or a GSM network to a GSM
`network, has already been described above and is likewise defined by the foreignness of the network
`based on the type of subscriber entry in the home subscriber register. In the case of session continuity,
`seamless access to these services across different access types is provided.
`
`Home and visited networks
`
`The differentiation between home network and visited network is technically given by the type of
`subscriber entry in a specific network. If a subscriber has no entry in the home subscriber register of the
`network (e.g. Home Location Register (HLR) in GSM networks or local customer database in WLANs),
`the required subscriber data must first be requested by the visited network e.g. from the subscriber's home
`network in order that the subscriber can be authenticated and any authorization for using the network
`services can be checked. The "visiting" subscriber acquires an entry in a user database of the visited
`network (e.g. Visited Location Register (VLR)) and the authorized network services are enabled. For the
`roaming procedure in practice, the possibility of assigning the subscriber data is always indispensable in
`order that authentication, authorization and billing of the subscriber can be performed in the
`corresponding network. Thus, the term roaming is not linked to a specific network standard, but rather to
`the type of subscriber entry in the home subscriber register of the mobile radio network. If a subscriber
`can use his personal service profile, which he uses in the home network, in the visited network as well,
`this is also referred to as Global Service Roaming Capability.
`
`Roaming agreements
`
`The legal roaming business aspects negotiated between the roaming partners for billing of the services
`obtained are usually stipulated in so called roaming agreements. The GSM Association broadly outlines
`the content of such roaming agreements in standardized form for its members. For the legal aspects of
`authentication, authorization and billing of the visiting subscriber, the roaming agreements typically can
`comprise minimal safety standards, as e.g. location update procedures or financial security or warranty
`procedures.
`
`The roaming process
`
`The details of the roaming process differ among types of cellular networks, but in general, the process
`resembles the following:
`
`Location Update
`
`Location updating is the mechanism that is used to determine the location of an MS in the idle state
`(Connected to the network, but with no active call).
`
`1. When the mobile device is turned on or is transferred via a handover to the network, this new
`"visited" network sees the device, notices that it is not registered with its own system, and attempts
`to identify its home network. If there is no roaming agreement between the two networks,
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`maintenance of service is impossible, and service is denied by the visited network.
`2. The visited network contacts the home network and requests service information (including
`whether or not the mobile should be allowed to roam) about the roaming device using the IMSI
`number.
`3. If successful, the visited network begins to maintain a temporary subscriber record for the device.
`Likewise, the home network updates its information to indicate that the cell phone is on the host
`network so that any information sent to that device can be correctly routed.
`
`Mobile Terminated Call
`
`It occurs for example when a call is made to a roaming cell phone.
`
`Signaling process:
`
`1. The calling subscriber (from within the public telephone network) dials the mobile subscriber's
`MSISDN (the telephone number) of the roaming cell phone.
`2. Based on the information contained in the MSISDN (national destination code and the country
`code), the call is routed to the mobile network gateway MSC (GMSC). It's done with an ISUP IAM
`message.
`3. To locate the MS, the GMSC sends to the HLR a MAP SRI (Send Routing Information) message.
`The MAP SRI message contains the MSISDN number and with this MSISDN the HLR will obtain
`the IMSI.
`4. Because of past location updates, the HLR already knows the VLR that currently serves the
`subscriber. The HLR will sent to the VLR a MAP PRN (Provide Roaming Number) message to
`obtain the MSRN of the roaming cell phone. Like that the HLR will be able to route the call to the
`correct MSC.
`5. With the IMSI contained in the MAP PRN message, the VLR assigns a temporary number known
`as the mobile station roaming number (MSRN) to the roaming cell phone. This MSRN number is
`sent back to the HLR in a MAP RIA (Routing Information Acknowledgement) message.
`6. Now with the MSRN number, the GMSC knows how to route the call to reach the roaming cell
`phone. Then, the call is made using ISUP ( or TUP) signaling between the GMSC and the visited
`MSC. The GMSC will generate an ISUP IAM message with the MSRN as the called party number
`(and NOT the MSISDN as the called party number).
`7. When the MSC of the visitor network receives the IAM, it recognizes the MSRN and knows the
`IMSI for which the MSRN was allocated. The MSC then returns the MSRN to the pool for future
`use on another call. Afterwards, the MSC sends to the VLR a MAP SI (Send Information) message
`to requeste information like the called MS's capabilities, services subscribed to, and so on. If the
`called MS is authorized and capable of taking the call, the VLR sends a MAP CC (Complete Call)
`message back to the MSC.
`
`In order that a subscriber is able to "latch" on to a visited network, a roaming agreement needs to be in
`place between the visited network and the home network. This agreement is established after a series of
`testing processes called IREG (International Roaming Expert Group) and TADIG (Transferred Account
`Data Interchange Group). While the IREG testing is to test the proper functioning of the established
`communication links, the TADIG testing is to check the billability of the calls.
`
`The usage by a subscriber in a visited network is captured in a file called the TAP (Transferred Account
`Procedure) for GSM / CIBER (Cellular Intercarrier Billing Exchange Record) for CDMA, AMPS etc ...
`file and is transferred to the home network. A T AP/CIBER file contains details of the calls made by the
`subscriber viz. location, calling party, called party, time of call and duration, etc. The TAP/ClBER files
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`are rated as per the tariffs charged by the visited operator. The home operator then bills these calls to its
`subscribers and may charge a mark-up/tax applicable locally. As recently many carriers launched own
`retail rate plans and bundles for Roaming, TAP records are generally used for wholesale Inter-Operators
`settlements only.
`
`Tariffs
`
`Roaming fees are traditionally charged on a per-minute basis and they are typically determined by the
`service provider's pricing plan. Several carriers in both the United States and India have eliminated these
`fees in their nationwide pricing plans. All of the major carriers now offer pricing plans that allow
`consumers to purchase nationwide roaming-free minutes. However, carriers define "nationwide" in
`different ways. For example, some carriers define "nationwide" as anywhere in the U.S., whereas others
`define it as anywhere within the carrier's network.
`
`An operator intending to provide roaming services to visitors publishes the tariffs that would be charged
`in his network at least sixty days prior to its implementation under normal situations. The visited operator
`tariffs may include tax, discounts etc. and would be based on duration in case of voice calls. For data
`calls, the charging may be based on the data volume sent and received. Some operators also charge a
`separate fee for call setup i.e. for the establishment of a call. This charge is called a flagfall charge.
`
`Roaming between European countries
`
`Main article: European Commission roaming regulations
`
`In the European Union, the Regulation on roaming charges has been in force since 30 June 2007, forcing
`service providers to lower their roaming fees across the 28-member bloc. It later also included EEA
`member states. The regulation sets a price cap of €0.39 (€0.49 in 2007, €0.46 in 2008, €0.43
`in 2009) per
`minute for outgoing calls, and €0.15 (€0.24
`in 2007, €0.22 in 2008, €0.19 in 2009) per minute for
`incoming calls - excluding tax_[l] If the Commission is satisfied that competition will continue to keep
`prices at this level, or lower, the regulation will expire in mid-2012. Since mid-2009 there is also an
`€0.11 (excluding tax) maximum price for SMS text message included into this regulation.
`
`On 11 June 2013, the European Commission voted to end mobile roaming charges. It is expected to come
`into force on 1 July 2014.[2]
`
`Roaming between other countries
`
`Countries that do not share a supra-national authority have also begun examining the provision of
`international roaming services. In April 2011, Singapore and Malaysia announced that they had agreed
`with operators to reduce voice and SMS rates for roaming between their two countries. [3] In August
`2012, Australia and New Zealand published a draft report proposing coordinated action on roaming
`services_[4] This was followed by a final report in February 2013 recommending that the two countries
`equip their telecommunications regulators with an extended palette of regulatory remedies, when they
`investigate international roaming_[S] The Australian and New Zealand Prime Ministers subsequently
`announced that they would introduce legislation to effect the recommendations of the final report. [6]
`
`Additional notions and types of roaming
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`(cid:127) Regional roaming:
`
`This type of roaming refers to the ability of moving from one region to another region inside national
`coverage of the mobile operator. Initially, operators may have provide commercial offers restricted to a
`region (sometimes to a town). Due to the success of GSM and the decrease in cost, regional roaming is
`rarely offered to clients except in nations with wide geographic areas like the USA, Russia, India, etc., in
`which there are a number of regional operators.
`
`(cid:127) National roaming:
`
`This type of roaming refers to the ability to move from one mobile operator to another in the same
`country. For example, a subscriber of T-Mobile USA who is allowed to roam on AT&T Mobility's
`service would have national roaming rights. For commercial and license reasons, this type of roaming is
`not allowed unless under very specific circumstances and under regulatory scrutiny. This has often taken
`place when a new company is assigned a mobile telephony license, to create a more competitive market
`by allowing the new entrant to offer coverage comparable to that of established operators (by requiring
`the existing operators to allow roaming while the new entrant has time to build up its own network). In a
`country like India, where the number of regional operators is high and the country is divided into circles,
`this type of roaming is common[citation neededJ_ Following the merger of Orange UK and T-Mobile UK on
`1 July 2010, national roaming has been possible between these two networks since 5 October 2010 at no
`additional cost pending the technical merging of the two networks.
`
`(cid:127)
`
`International roaming:
`
`This type of roaming refers to the ability to move to a foreign service provider's network. It is,
`consequently, of particular interest to international tourists and business travellers.
`
`Broadly speaking, international roaming is easiest using the GSM standard, as it is used by over 80% of
`the world's mobile operators. However, even then, there may be problems, since countries have allocated
`different frequency bands for GSM communications (there are two groups of countries: most GSM
`countries use 900/1800 MHz, but the United States and some other countries in the Americas have
`allocated 850/1900 MHz): for a phone to work in a country with a different frequency allocation, it must
`support one or both of that country's frequencies, and thus be tri or quad band.
`
`(cid:127)
`
`Inter-standards roaming:
`
`Inter Standard Roaming refers to roaming between two standards. This term is now widely used in
`mobile communnications where especially CDMA customers want to use their phone in areas where
`there is no CDMA network or there is no roaming agreement in place to support roaming on the used
`standard. In Europe there is hardly any CDMA network. Most CDMA customers originate from the
`Americas or the Far East. In order to enable them to roam in Europe Inter Standard Roaming is the
`solution. The CDMA customers arriving in Europe can register on the available GSM networks.
`
`Since mobile communication technologies have evolved independently across continents, there is
`significant challenge in achieving seamless roaming across these technologies. Typically, these
`technologies were implemented in accordance with technological standards laid down by different
`industry bodies and hence the name.
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`A number of the standards making industry bodies have come together to define and achieve
`interoperability between the technologies as a means to achieve inter-standards roaming. This is currently
`an ongoing effort.
`
`(cid:127) Mobile Signature Roaming:
`
`Mobile signature Roaming allows an access point to get a Mobile Signature from any end-user, even if
`the AP and the end-user have not contracted a commercial relationship with the same MSSP. Otherwise,
`an AP would have to build commercial terms with as many MSSPs as possible, and this might be a cost
`burden. This means that a Mobile Signature transaction issued by an Application Provider should be able
`to reach the appropriate MSSP, and this should be transparent for the AP(reference).
`
`(cid:127)
`
`Inter MSC Roaming[7l
`
`Network elements belonging to the same Operator but located in different areas (a typical situation where
`assignment of local licenses is a common practice )pair depends on the switch and its location.Hence,
`software changes and a greater processing capability are required, but furthermore this situation could
`introduce the fairly new concept of roaming on a per MSC basis instead of per Operator basis. But this is
`actually a burden, so it is avoided.
`
`(cid:127) Permanent Roaming:
`
`This type of roaming refers to customers who purchase service with a mobile phone operator intending to
`permanently roaming, or be off-network. This becomes possible because of the increasing popularity and
`availability of "free roaming" service plan, where there is no cost difference between on and off network
`usage. The benefits of getting service from a mobile phone operator that isn't local to you can include
`cheaper rates, or features and phones that aren't available on your local mobile phone operator, or to get
`to a particular mobile phone operator's network to get free calls to other customers of that mobile phone
`operator through a free unlimited mobile to mobile feature. To accidentally become a permanent roaming
`customer does not usually happen. Most mobile phone operators will require the customer's living or
`billing address be inside their coverage area or less often inside the government issued radio frequency
`license of the mobile phone operator, this is usually determined by a computer estimate because it is
`impossible to guarantee coverage. If a potential customer's address is not within the requirements of that
`mobile phone operator, they will be denied service. In order to permanently roam customers may use a
`false address and online billing, or a relative or friends address which is in the required area, and a 3rd
`party billing option.
`
`Most mobile phone operator discourage or prohibit permanent roaming since they must pay per minute
`rates to the network operator their customer is roaming onto to, [S] while they can not pass that extra cost
`onto customers ("free roaming").
`
`(cid:127) Trombone roaming:
`
`Roaming calls within a local tariff area, when at least one of the phones belong outside that area. Usually
`implemented with trombone routing[9] also known as tromboning[IO]
`
`The routing of trombone roaming.
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`See also
`
`(cid:127)
`
`IEEE 802.11
`IEEE 802. llf
`(cid:127)
`IEEE 802. llr
`(cid:127)
`(cid:127) Home Location Register
`(cid:127) Handoff
`(cid:127) Mobile IP
`(cid:127) Mobile phone
`(cid:127) Mobile phones on aircraft
`(cid:127) Mobility management
`(cid:127) Regulation on roaming charges in the European Union
`(cid:127) Roaming sim
`(cid:127) GSM frequency bands
`(cid:127) UMTS frequency bands
`(cid:127) Vertical handoff
`(cid:127) Visitor Location Register
`(cid:127) Starhome
`
`References
`
`1.
`2.
`
`3.
`4.
`
`5.
`
`6.
`7.
`
`8.
`
`A "New caps on roaming charges in place for August", 8 June 2007
`A Williams, Christopher (2013-06-13). "EU to end mobile roaming charges next year". The Telegraph.
`Retrieved 2013-06-30.
`A [l]
`A "Trans-Tasman Roaming - Draft Report". Ministry of Business, Innovation and Employment. Retrieved
`2013-06-30.
`[ www .med.govt.nz/sectors-industries/technology-communication/communications/mobile-phones/trans(cid:173)
`A
`tasman-roaming]
`A [www.pm.gov.au/press-office/joint-statement-prime-ministers-key-and-gillard-february-2013]
`A "Signalling interoperability as a key enabler to GSM/PCS roaming with North America". IEEE Xplore.
`doi: 10. l 109NETEC.1998.686490. Retrieved 2013-06-30.
`A Roaming-Included Plans: .... Sprint may terminate service if (1) more than 800 minutes, (2) a majority of
`minutes or (3) a majority of data kilobytes in a given month are used while roaming. [2] Termination By Us
`We may limit, interrupt, terminate or refuse to provide a Service for the following reasons, or for any other
`good cause: .... (j) if the majority of your Service is used roaming on a network not owned or operated by
`Alltel. [3] OFF-NET USAGE If your minutes of use (including unlimited services) on other carrier networks
`("off-net usage'') during any two consecutive months exceed your off-net usage allowance, AT&T may, at its
`option terminate your service, deny your continued use of other carriers' coverage or change your plan to one
`imposing usage charges for off-net usage. Your off-net usage allowance is equal to the lesser of750 minutes
`or 40% of the Anytime Minutes included with your plan. AT&T will provide notice that it intends to take any
`of the above actions, and you may terminate the agreement. [4] Zeman, Eric (Nov 20, 2007). "I-Mobile
`Dumps Customers Who Roam Too Much". Information Week. Retrieved 2008-03-15. b. Roaming Services.
`Roaming services typically refers to coverage on another carrier's network that we make available to you
`based on our agreements with other carriers. If your minutes of use for roaming services during any two
`consecutive months exceeds a reasonable roaming usage allowance or if a majority of minutes in a given
`month are used while roaming, we may, at our sole option, terminate your Services, deny your continued use
`of roaming services, or change your plan to one imposing usage charges for roaming services. Your roaming
`usage allowance is equal to the lesser of (i) 300 minutes or (ii) 30% of the anytime minutes included in your
`plan. In the event that we intend to take any of the above actions, we will provide you with prior notice, and
`you may choose to terminate your Customer Agreement without incurring any additional fees for termination.
`[5] Additional Terms .... Customers must have a mailing address and live in Centennial 's Primary Service
`Area. Centennial Wireless may discontinue your service if, over two consecutive billing cycle, any of the
`following apply: 40% of airtime minutes or 750 minutes of usage are incurred outside Centennial-owned
`
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`9.
`10.
`
`systems; there is excessive use of free minutes from included callingfeatures .... [6] [7] ).
`A PHS MoU Group: Note - Trombone Rooting
`A Competition Commission: Telephone number portability: A report on a reference under section 13 of the
`Telecommunications Act 1984
`
`Standardisation Organizations
`
`(cid:127) ETSI website, European Telecommunications Standards Institute.
`(cid:127) Direct access to ETSI standards publications.
`(cid:127) GSM website, Global System for Mobile communications by the GSM Association (GSMA)
`
`External links
`
`(cid:127) Roaming - Using my mobile abroad: are prices dropping ? - European Commission
`Intra MSC Roaming
`(cid:127)
`(cid:127) Mobile Europe describes how the roaming industry will cope with pending EU legislation and the
`arrival of mobile VoIP
`(cid:127) GSM operators and their roaming agreements - Index of GSM operators in a country, and their
`roaming partners indexed by country. Maintained by GSM Alliance
`
`Retrieved from "http://en.wikipedia.org/w/index.php?tit1e=Roaming&oldid=562457974"
`Categories: GSM standard • Mobile technology
`
`(cid:127) This page was last modified on 1 July 2013 at 22: 13.
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