TECHNOLOGY TRENDS

MULTI TASKING IP MULTIMEDIA SUBSYSTEMS

IMS is finding favour among mobile operators moving to LTE that want to protect voice revenues, but there are technical and process challenges ahead. By Roy Rubenstein

ogy is finally placing IP Multimedia Subsystem (IMS) at the core of the network. IMS will add voice and multi- media telephony services to LTE using Voice over LTE (VoLTE), helping mobile operators to ward off competition for their core revenue-generating services. But mobile operators also face a

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dilemma: while they implement IMS and VoLTE, the communications providers whose services run over their networks will benefit from LTE broadband without the challenges associated with IMS deployment. Mobile operators adopting IMS-based VoLTE will need to ensure that the resulting services match the quality of circuit-switched voice, and while they take time to do this over-the- top providers can advance their offerings, says Dan Warren, senior director of tech- nology at the GSM Association (GSMA). “The challenge is that the length of time

it takes to generate sufficient inter-opera- tor interconnect and roaming, as well as the handsets, is time during which the likes of Skype, Google, Viber and Fring are developing new things.” These Internet players move quickly because they don’t

Worldwide IMS equipment revenues $1.6 billion

confluence of events surrounding the deployment of Long Term Evolution (LTE) wireless technol-

have to worry about fallback to the circuit- switched domain or interconnect to other players, he says. “All of that stuff will be taking place while mobile operators are getting onto the VoLTE page.” IMS was envisaged a decade ago as an

over-arching core signalling and control architecture upon which new services would be developed and delivered across various access networks. In reality, opera- tors reacted cautiously to the technology. “The general problem was that IMS

required a significant reworking of the network,” says Dimitris Mavrakis, senior analyst, networks, at Informa Telecoms & Media. “It involved replacing or refreshing services that generated reve- nues.” Operators had no reason to replace infrastructure that was working well and generating revenues even if IMS prom- ised greater efficiencies. And while operators grappled with how

to make money from services such as instant messaging and video telephony, Internet-based services came along to deliver such services cost-effectively or even for free. Some mobile operators such as Japan’s

NTT DoCoMo and Korea’s SK Telecom (see box p.10) have continually developed enhanced multimedia services using IMS,

while the likes of Vodafone and A1 Telekom Austria (formerly Mobilkom Austria) have launched enterprise serv- ices. But the main IMS deployments to date have been in the fixed network. “What IMS has become is the next-

generation VoIP platform,” says Diane Myers, directing analyst, VoIP and IMS, at Infonetics Research. In part that is because vendors have adopted IMS for their voice products. France Telecom has used IMS for voice

as part of its triple-play services, respond- ing to competitive operators’ offerings, and now has several million VoIP subscribers. “France Telecom started to decommission its service-switched lines as subscribers began actively moving from their traditional phone line to their bundled service,” says Myers. Other operators are moving to VoIP

using IMS switches to achieve opera- tional savings as they replace their Class 5 PSTN switches. China’s operators including China Telecom have been mandated to do this, says Myers, as the Chinese government looks to reduce the country’s power requirements. “Class 5 switches are large, monolithic boxes that consume a lot of power. You have to have them located in different points of pres- ence; they can’t be run off one central location,” she says. Yet operators do have the option of

$176 million 2008 2009 2010 2011 2012 2013 2014 2015 Source: Infonetics Research 8

staying with a next-generation network (NGN) softswitch architecture, rather than adopting IMS, when delivering VoIP. “There are operators where deploying IMS makes sense, but if your first step is VoIP, deploy NGN, and deploy IMS only when you need to offer multimedia serv- ices,” says Ali Kafel, product marketing & business development, Sonus Networks. Colt Technology Services is one fixed-

line operator that has adopted Sonus’ softswitch platform for VoIP, but it is also incorporating elements of IMS. “What we do with IMS is slightly different to what others do with IMS,” says Nicolas

www.totaltele.com September 2011