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Generic Access NetworkFrom Wikipedia, the free encyclopedia

Generic Access Network or GAN is a telecommunication system that extends mobile voice, data and multimedia(IMS/SIP) applications over IP networks. Unlicensed Mobile Access or UMA, is the commercial name used bymobile carriers for external IP access into their core networks. More recently, the system has been called Wi-FiCalling by a number of handset manufacturers, including Apple and Samsung, a move that is being mirrored bycarriers like T-Mobile US.

Essentially, GAN allows cell phone packets to be forwarded to a network access point over the internet, ratherthan over-the-air using GSM/GPRS, UMTS or similar. A separate device known as a "GAN Controller" (GANC)receives this data from the internet and feeds it into the phone network as if it were coming from an antenna on atower. Calls can be placed from or received to the handset as if it were connected over-the-air directly to theGANC's point of presence. The system is essentially invisible to the network as a whole.

In its most common form, GAN is used to allow UMA-compatible mobile phones to use WiFi networks to connectcalls, in place of conventional cell towers. This can be useful in locations with poor cell coverage where some otherform of internet access is available, especially at the home or office. The system offers seamless handoff, so the usercan move from cell to WiFi and back again with the same invisibility that the cell network offers when moving fromtower to tower.

Since the GAN system uses the standard IMS/SIP protocols for setting up calls (dialling) and other controlfeatures, it is also possible to use a UMA phone to talk to a private phone network. A common use involves anAsterisk private branch exchange (PBX) system connected to a WiFi router, allowing people in the office to makecalls though the company phone system using their cell handsets. This gives them all the features they would have ona conventional office phone, like extension forwarding and call parking. When they leave the office the phonenaturally switches over to the cell network of their choice. This can also allow the user to connect to their PBXsystem remotely over the internet, allowing, for instance, calls to be made out of their office while on a trip or athome.

Since the GAN system works over the internet, a UMA-capable handset can connect to their service providerfrom any location with internet access. This is particularly useful for travellers, who can connect to their provider'sGANC and make calls into their home service area from anywhere in the world. This is subject to the quality of theinternet connection, however, and may not work well over limited bandwidth or long-latency connections. Toimprove quality of service in the home or office, some providers also supply a specially programmed wirelessaccess point that prioritizes UMA packets.

Contents

1 History

2 Modes of operation

3 Advantages

4 Disadvantages

5 Service deployments

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A UMA-enabled handset. When using

UMA (top) the phone displays an

SSID and a different signal strength

indicator.

6 UMA/GAN Beyond Dual-mode

7 Similar technologies

8 Devices

9 See also

10 References

11 External links

History

UMA was developed by a group of operator and vendor companies.[1]

The initial specifications were published on 2 September 2004. Thecompanies then contributed the specifications to the 3rd Generation Partnership Project (3GPP) as part of 3GPPwork item "Generic Access to A/Gb interfaces". On 8 April 2005, 3GPP approved specifications for Generic

Access to A/Gb interfaces for 3GPP Release 6. [2] and,[3] and renamed the system to GAN. But the term GAN islittle known outside the 3GPP community, and the term UMA is more common in marketing.

Modes of operation

The original Release 6 GAN specification supported a 2G (A/Gb) connection from the GANC into the mobile corenetwork (MSC/GSN). Today all commercial GAN dual-mode handset deployments are based on a 2G connectionand all GAN enabled devices are dual-mode 2G/Wi-Fi. The specification, though, defined support for multimodehandset operation. Therefore, 3G/2G/Wi-Fi handsets are supported in the standard. The first 3G/UMA deviceswere announced in the second half of 2008.

A typical UMA/GAN handset will have four modes of operation:

GERAN-only: uses only cellular networks

GERAN-preferred: uses cellular networks if available, otherwise the 802.11 radio

GAN-preferred: uses an 802.11 connection if an access point is in range, otherwise the cellular network

GAN-only: uses only the 802.11 connection

In all cases, the handset scans for GSM cells when it first turns on, to determine its location area. This allows thecarrier to route the call to the nearest GANC, set the correct rate plan, and comply with existing roamingagreements.

At the end of 2007, the GAN specification was enhanced to support 3G (Iu) interfaces from the GANC to themobile core network (MSC/GSN). This native 3G interface can be used for dual-mode handset as well as 3Gfemtocell service delivery. The GAN release 8 documentation describes these new capabilities.

Advantages

For carriers:

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Instead of erecting expensive base stations to cover dead zones, GAN allows carriers to add coverage using

low cost 802.11 access points. Subscribers at home have very good coverage.

In addition, GAN relieves congestion (meaning that networks can, through GAN, essentially piggyback on

other infrastructure) on the GSM or UMTS spectrum by removing common types of calls and routing them

to the operator via the relatively low cost Internet

GAN makes sense for network operators that also offer Internet services. Operators can leverage sales of

one to promote the other, and can bill both to each customer.

Some other operators also run networks of 802.11 hotspots, such as T-Mobile. They can leverage these

hotspots to create more capacity and provide better coverage in populous areas.

The carrier does not pay for much of the service, the party who provides the Internet and Wi-Fi connection

pays for a connection to the Internet, effectively paying the expensive part of routing calls from the

subscriber.

For subscribers:

Subscribers do not rely on their operator's ability to roll out towers and coverage, allowing them to fix some

types of coverage dead zones (such as in the home or workplace) themselves.

The cheaper rates for 802.11 use, coupled with better coverage at home, make more affordable and

practical the use of cellphones instead of land lines.

Using IP over 802.11 eliminates expensive charges when roaming outside of a carrier's network.

GAN is currently the only commercial technology available that combines GSM and 802.11 into a service

that uses a single number, a single handset, a single set of services and a single phone directory for all calls.

GAN can migrate between IP and cellular coverage and is thus seamless; in contrast, calls via third-party

VOIP plus a data phone are dropped when leaving high-volume data coverage.

Disadvantages

Subscribers must upgrade to Wi-Fi/UMA enabled handsets to take advantage of the service.

Calls may be more prone to disconnect when the handset transitions from Wi-Fi to the standard wireless

service and vice versa (because the handset moved out or within the Wi-Fi's range). How much this is a

problem may vary based on which handset is used.

The UMA may use different frequency that is more prone to some types of interference

Some setup may be required to provide connection settings (such as authentication details) before

advantages may be experienced. This may take time for subscribes and require additional support to be

provided. The costs of support may be for more than the wireless phone company: network administrators

may be asked to help a user enter appropriate settings into a phone (that the network administrator may

know little about).

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The phones that support multiple signals (both the UMA/Wi-Fi and the type of signal used by the provider's

towers) may be more expensive, particularly to manufacture, due to additional circuitry/components required

This uses the resources of the network providing the Wi-Fi signal (and any indirect network that is then

utilized when that network is used). Bandwidth is used up. Some types of network traffic (like DNS and

IPsec-encrypted) need to be permitted by the network, so a decision to support this may impose some

requirement(s) regarding the network's security (firewall) rules.

Using GAN/UMA on a mobile requires the WiFi module to be enabled. This in turn drains the battery faster,

and reduces both the talk time and standby time when compared to disabling GAN/UMA (and in turn WiFi).

Service deployments

The first service launch was BT with BT Fusion in the autumn of 2005. The service is based on pre-3GPP GANstandard technology. Initially, BT Fusion used UMA over Bluetooth with phones from Motorola; since Jan 2007, it

has used UMA over 802.11 with phones from Nokia, Motorola and Samsung[4] and is branded as a "Wi-Fimobile service". BT has since discontinued the service.

On August 28, 2006, TeliaSonera was the first to launch an 802.11 based UMA service called "Home Free".[5]

The service started in Denmark but no longer offered.

On September 25, 2006 Orange announced its "Unik service", also known as Signal Boost in the UK.[6][7] Theannouncement, the largest to date, covers more than 60m of Orange's mobile subscribers in the UK, France,Poland, Spain and the Netherlands.

Cincinnati Bell announced the first UMA deployment in the United States.[8] The service, originally called CBHome Run, allows users to transfer seamlessly from the Cincinnati Bell cellular network to a home wireless networkor to Cincinnati Bell's WiFi HotSpots. It has since been rebranded as Fusion WiFi.

This was followed shortly by T-Mobile US on June 27, 2007.[9] T-Mobile's service, originally named "HotspotCalling", and rebranded to "Wi-Fi Calling" in 2009, initially allowed users to seamlessly transfer from the T-Mobilecellular network to an 802.11x wireless network or T-Mobile HotSpot in the United States. However, the currentversion of WiFi Calling no longer supports handoff.

In Canada, both Fido and Rogers Wireless launched UMA plans under the names UNO and Rogers Home CallingZone (later rebranded Talkspot, and subsequently rebranded again as Wi-Fi Calling), respectively, on May 6,

2008.[10]

Industry organization UMA Today tracks all operator activities and handset development.

UMA is not implemented in Asia, Australia, Africa and some European countries.

UMA/GAN Beyond Dual-mode

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While UMA is nearly always associated with dual-mode GSM/Wi-Fi services, it is actually a ‘generic’ accessnetwork technology that provides a generic method for extending the services and applications in an operator'smobile core (voice, data, IMS) over IP and the public Internet.

GAN defines a secure, managed connection from the mobile core (GANC) to different devices/access points overIP.

Femtocells - The GAN standard is currently used to provide a secure, managed, standardized interface from afemtocell to the mobile core network. Recently Kineto, NEC and Motorola issued a joint proposal to the 3GPPwork group studying femtocells (also known as ‘Home Node B's or HNB) to propose GAN as the basis for thatstandard.

Analog Terminal Adaptor – T-Mobile US once offered a fixed-line VoIP service called @Home.[11] Similar toVonage, consumers can port their fixed phone number to T-Mobile. Then T-Mobile associates that number with anATA (analog telephone adapter). The consumer plugs the ATA into a home broadband network and beginsreceiving calls to the fixed number over the IP access network. The service was discontinued in 2010, however

earlier subscribers were "grandfathered" in.[12]

Mobile VoIP Client - Consumers have started to use telephony interfaces on their PCs. Applications offer a lowcost, convenient way to access telephony services while traveling. Now mobile operators can offer a similar servicewith a UMA-enabled mobile VoIP client. Developed by Vitendo, the client provides a mirror interface to asubscriber's existing mobile service. For the mobile operator, services can now be extended to a PC/laptop, andthey can give consumers another way to use their mobile service.

Similar technologies

GAN/UMA is not the first system to allow the use of unlicensed spectrum to connect handsets to a GSM network.The GIP/IWP standard for DECT provides similar functionality, but requires a more direct connection to the GSMnetwork from the base station. While dual-mode DECT/GSM phones have appeared, these have generally beenfunctionally cordless phones with a GSM handset built-in (or vice versa, depending on your point of view), ratherthan phones implementing DECT/GIP, due to the lack of suitable infrastructure to hook DECT base-stations

supporting GIP to GSM networks on an ad-hoc basis.[13]

GAN/UMA's ability to use the Internet to provide the "last mile" connection to the GSM network solves the majorissue that DECT/GIP has faced. Had GIP emerged as a practical standard, the low power usage of DECTtechnology when idle would have been an advantage compared to GAN.

There is nothing preventing an operator from deploying micro- and pico-cells that use towers that connect with thehome network over the Internet. Several companies have developed so-called Femtocell systems that do preciselythat, broadcasting a "real" GSM or UMTS signal, bypassing the need for special handsets that require 802.11technology. In theory, such systems are more universal, and again require lower power than 802.11, but theirlegality will vary depending on the jurisdiction, and will require the cooperation of the operator. Further, users maybe charged at higher cell phone rates, even though they are paying for the DSL or other network that ultimatelycarries their traffic; in contrast, GAN/UMA providers charge reduced rates when making calls off the providerscellular phone network.

Devices

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Apple - iPhone 4S, iPhone 5, iPhone 5c, iPhone 5S with iOS 8.[14]

BlackBerry - Curve 8320, 8520, 8820, Curve 8900, Pearl 8120 and 8220, Bold 9700, Bold 9780, Torch

9800, Blackberry 9105, 9300, Blackberry Bold 9900 with OS 7.1[15]

HTC - Touch 3G,[16] T-Mobile Shadow 2009, T-Mobile myTouch 4G (sometimes called the myTouch

HD),[17] T-Mobile G2 (as of build 1.22.531.8 OTA update), Desire S,[18] Wildfire S, Sensation 4G, Amaze

4G, HTC One, HTC One S

Huawei - U8651T[19]

LG - KE 520, KF 757 (3G), GT505, Optimus One,[20] LG Optimus Me

Motorola - DEFY,[21] Z6w

Nokia[22] - 6300i, 6301, 6301b, 6086, 6136, 7510, E73 Mode, E5, C7 Astound, Lumia 521,[23] Lumia

925[24]

Sagem - my419X

Samsung[25] - SGH-T339, SGH-T409, SGH-T709, SGH-T739 (Katalyst), T336, P250, P260, P270

(3G), T-Mobile's Galaxy S SGH-T959, Galaxy SII SGH-T989, Orange Galaxy SII with NFC (GT-

i9100P), T-Mobile's Galaxy S4 SGH-M919

Sony Ericsson - G705u (3G)

Routers

Linksys WRT54G series#WRT54G-TM

Westell - UltraVoice UMA Terminal Adapter with Router

See also

Femtocell

IEEE 802.21

IEEE 802.11r

IEEE 802.11u

Mobile VoIP

MOIP

VoWLAN

BT Fusion

References

1. ^ UMA Today (http://www.umatoday.com/links.php)

2. ^ TS 43.318 (ftp://ftp.3gpp.org/Specs/archive/43_series/43.318/)

3. ^ TS 44.318 (ftp://ftp.3gpp.org/Specs/archive/44_series/44.318/)

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3. ^ TS 44.318 (ftp://ftp.3gpp.org/Specs/archive/44_series/44.318/)

4. ^ The Register:BT Fusion goes Wi-Fi (http://www.theregister.co.uk/2007/01/08/bt_fusion_wifi/)

5. ^ Home Free (http://telia.dk/privat/produkter/homefree)

6. ^ Unik in France (http://www.unik.orange.fr)

7. ^ Unik in the UK (http://www.orange.co.uk/unique/)

8. ^ CB Home Run Integrates Mobile Phone and Wireless Internet For Improved Indoor Reception

(http://www.cincinnatibell.com/aboutus/news/articles/news.asp?page=20070618.asp)

9. ^ T-Mobile Introduces Unlimited Calling Over Wi-Fi With the National Launch of T-Mobile HotSpot @Home

(http://www.t-mobile.com/company/PressReleases_Article.aspx?assetName=Prs_Prs_20070627&title=T-

Mobile%20Introduces%20Unlimited%20Calling%20Over%20Wi-

Fi%20With%20the%20National%20Launch%20of%20T-Mobile%20HotSpot%20@Home)

10. ^ CNW Group Fido's home and mobile calling are now 'UNO' with one phone, one number and one bill

(http://www.newswire.ca/en/releases/archive/May2008/06/c5578.html/)

11. ^ T Mobile @Home (http://www.t-mobileathome.com)

12. ^ T Mobile @Home discontinued (http://www.engadget.com/2010/01/12/t-mobile-killing-hotspot-home-service-

softly/)

13. ^ DECT Web DECT/GSM DUAL MODE and the advent of the ONEPHONE SERVICE

(http://www.dectweb.com/News&Views/Features/9906Dectweb.htm)

14. ^ "iOS 8 to feature Wi-Fi calling [Update - T-Mobile Confirms, it's coming!]"

(http://www.tmonews.com/2014/06/ios-8-to-feature-wi-fi-calling/). TmoNews. 2014-06-02. Retrieved 2014-06-

02.

15. ^ Leaked BlackBerry 9900 ROM adds Wi-Fi Hotspot, Wi-Fi calling features

(http://www.afterdawn.com/news/article.cfm/2011/11/27/leaked_blackberry_9900_rom_adds_wi-fi_hotspot_wi-

fi_calling_features)

16. ^ [1] (http://www.smart-wi-fi.com/mobileHandsetsHTCTouch3G.php)

17. ^ T-Mobile Extends Wi-Fi Calling to Android Smartphones (Press Release) (http://press.t-mobile.com/articles/t-

mobile-android-wifi-calling)

18. ^ Orange Launch the HTC Desire S with Signal Boost (UMA) (http://www.store-orange.co.uk/orange-htc-desire-

s.html)

19. ^ http://www.huaweidevice.com/worldwide/productFeatures.do?

pinfoId=3403&directoryId=6001&treeId=3745&tab=0

20. ^ Orange launch the LG Optimus One with UMA (http://www.tracyandmatt.co.uk/blogs/index.php/orange-launch-

the-lg-optimus-one-with-um)

21. ^ T-Mobile Extends Wi-Fi Calling to Android Smartphones (Press Release) (http://press.t-mobile.com/articles/t-

mobile-android-wifi-calling)

22. ^ http://reviews.ebay.com/T-Mobile-HotSpot-amp-Home-Phones-UMA-Updated-30-05-10?

ugid=10000000008431233

23. ^ http://www.tmonews.com/2013/05/t-mobile-announces-retail-availability-for-lumia-521-wi-fi-calling-and-all/

24. ^ http://www.youtube.com/watch?feature=player_embedded&v=k7e3wlYglZI

25. ^ http://reviews.ebay.com/T-Mobile-HotSpot-amp-Home-Phones-UMA-Updated-30-05-10?

ugid=10000000008431233

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External links

Orange Signal Boost (UMA) (http://shop.orange.co.uk/shop/show/offer/uma)

3GPP GAN Specification 43.318 (http://www.3gpp.org/ftp/Specs/html-info/43318.htm), 3GPP GAN

Specification 44.318 (http://www.3gpp.org/ftp/Specs/html-info/44318.htm)

Smart Wi-Fi (formerly UMAToday.com) (http://www.smart-wi-fi.com/) — contains also a list of available

GAN handsets

UMA Technology (http://www.umatechnology.org/overview/index.htm)

T-Mobile USA Wi-Fi Calling FAQs (http://support.t-mobile.com/doc/tm24195.xml?

related=y&Referring%20Related%20DocID%20List%20Index=4&navtypeid=6&pagetypeid=7&prevPage

Index=1)

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