Analysis - IMS Gets Boost from Voice over LTE

Sun, 11/29/2009 - 8:10pm
Keith Mallinson
IMS has struggled to find its justification,
whereas much of what end-users actually want is already being delivered
with Web-based and proprietary technologies on fixed and wireless networks.

Will solving the thorny problem of providing voice and SMS with LTE justify IMS investments and provide the competitive edge IMS desperately needs to become a major basis for rich service delivery on mobile networks?

The One Voice initiative aims to provide carrier grade voice and SMS on IP-based next-generation mobile networks. Wireless carriers and telecom equipment manufacturers AT&T, Orange, Telefonica, TeliaSonera, Verizon, Vodafone, Alcatel-Lucent, Ericsson, Nokia Siemens Networks, Nokia, Samsung and Sony Ericsson are onboard. This is significant with the migration to LTE because LTE has no circuit-switched voice capability. Whereas One Voice is based on existing Keith Mallinson3GPP IMS standards, it is currently an independent initiative with the objective of standards group adoption downstream. Sponsors claim it will ensure the widest possible ecosystem for LTE, avoiding technology fragmentation, securing interoperability and global roaming for voice and SMS over LTE. One Voice seeks to simplify and clarify the complex and unwieldy IMS.

Developments and carrier investments in IMS are probably justified because there is no other long-term solution for carrier-grade voice and SMS over LTE. Whereas IMS is not the only solution to the problem of dealing with LTE users’ voice calls and text messages, neither of the two alternative techniques being proposed by the mobile technology and carrier community exploits the rationalization that LTE’s all-IP architecture promises. Falling back to the circuit-switched networks for voice and text – and taking LTE data sessions down to an HSPA or even a GPRS/EDGE network in the process – is highly inconvenient and undesirable for the end-user. The other approach is a proprietary system, backed by T-Mobile and others, called Voice over LTE via Generic Access (VoLGA). VoLGA channels voice and SMS through LTE’s IP-centric core network using existing UMA capabilities that are already used to make calls over Wi-Fi connections.

The One Voice announcement broke while I was chairing the opening keynote session at Informa’s LTE Americas conference in Dallas. It caused quite a stir as speakers were either caught off guard by it or hurriedly prepared for the ensuing questions. Steve Shaw of VoLGA backer Kineto Wireless admits that the ultimate goal is IMS telephony. He explained the need for an interim solution, particularly for those carriers that are not  yet ready to commit to IMS. He said that VoLGA has always billed itself as the best path to IMS.

VoLGA as a solution to quit circuit-switched voice habits is rather like taking methadone in order to give up heroin. The former provides a pathway for the latter, but with no guarantees on when the final outcome will be achieved and significant dependency in the meantime. If widely adopted, VoLGA could enjoy a long life as carriers stall or relapse versus their long-term objective.

But perhaps the biggest threat of all in the long run is from elsewhere? Internet telephony over 3G works quite well some of the time using none of the above. In the case of Skype on my laptop, it can chew up several times more bandwidth than a circuit-switched connection. This unofficial and unwelcome use of carriers’ 3G networks for VoIP is quite different to what’s offered, for example, by H3G in the United Kingdom, where a circuit-switched bearer is used to connect to Skype’s servers.  With the prevailing wind for network neutrality encouraging unofficial use and the popularity of smartphones, Internet telephony on wireless might one day have as much impact – on market prices if not on market shares – as it does on the fixed networks today. Where VoIP providers can ride for free on networks that are priced for large volumes of data including flat rates, it makes cell phone minutes as well as fixed network minutes an attractive cash cow to attack.

Internet telephony is a classic disruptive technology, with reduced performance versus what it replaces, but at much lower prices. I have been doing most of my business calling over Skype on the fixed Internet for years. It is not carrier grade, but it works pretty well most of the time and on the odd occasion it does not, I have plenty of backup options for which the occasional calling costs me very little overall. In one sense, the competitive challenge is yet lower with cellular because poor connections are still commonplace, even with circuit-switching.

IMS has had high ambitions in mobile, as well as in fixed communications, including presence, IM, video and more. Results have been disappointing so far with the technology still grasping to find a core service to anchor its tenancy with wireless carriers while competitive solutions abound.

Mallinson is founder of WiseHarbor, solving commercial problems in wireless and mobile communications,


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