In my last post I discussed the return of IMS as part of the roll-out of voice over LTE (VoLTE). Of course an essential component of VoLTE will be handsets that support LTE and have a SIP user agent (UA). Conventional wisdom is that LTE deployments will initially be data only and handsets will follow some time later. Over the last several weeks I’ve been trying to understand just when LTE handsets will be available. I just returned from the CTIA wireless show here in the US and one of my objectives was to learn a bit more about the roadmap for LTE handsets with voice support.
For the most part the people I talked to were unwilling to reveal too much detail about their specific plans, but did generally agree that LTE deployments will start with data cards and handsets will follow. Estimates were that handsets would be available as early as 2011 and Verizon Wireless recently announced they would have handsets in 2011. On the other hand, a colleague that attended some of the keynote speeches indicated that a couple of the carriers seemed to imply that VoLTE in the 2012 timeframe was a reasonable assumption.
Surprisingly, I also found that Samsung made an announcement that they would have an LTE handset in 2010. The press release can be found HERE.
The phone, a Samsung SCH-r900, will be an LTE-enabled multi-mode handset that also supports CDMA. It will be available in the second half of 2010 for MetroPCS’ LTE deployment in Las Vegas. While few details were made available, it is conceivable that this phone will support voice over LTE – but there is the possibility that it will only use LTE for data only. The announcement wasn’t definitive on this point.
There are of course many issues and challenges to solve with respect to VoLTE handsets – especially in CDMA networks. The complexities include radio issues, the implementation of SIP UAs and SIP compression (SIGCOMP). But just as important are the issues associated with voice call handover – in particular handover between different radio access technologies, e.g. CDMA and LTE. This creates challenges in both the network and the handset.
Another interesting challenge in the handset will be the design of the SIP UA in the handset. Our experiences in early IMS trials showed that many of the handsets had a separate SIP stack for every application on the handset. This could mean one SIP stack for voice calls and another for messaging applications or RCS (Rich Communications Suite). It would also mean multiple registrations with the network for each application. This is probably not the ideal situation from the carrier perspective – but presumably things have evolved in the last 5 or so years since the early IMS trials.
In conclusion, it would appear as though momentum is continuing to grow for LTE and the availability of handsets is exceeding my initial expectations – but it is still early. LTE deployment will take years (if not a couple of decades) to reach a large percentage of subscribers. We should remember that at the end of 2009, 3G subscribers were estimated to comprise only 17% of the total worldwide mobile subscriber base, according to Portio Research. However, the growth of mobile data is pushing many carriers in developed economies to take a close look at deploying LTE sooner as opposed to later.