The more I think about it the more I am convinced that voice service will make or break LTE in the mid-term. While most industry observers agree that the first devices for LTE are likely to be USB dongles and PC cards the real LTE story only starts once the technology makes it into mobile Internet devices and handsets.
While on mobile Internet devices it might be acceptable to have Skype or some other VoIP technology, smaller handsets who's main purpose is voice service might have a much more difficult time with VoIP. Such devices must also be capable of roaming to 2G and 3G networks when running out of LTE coverage. Especially in 2G networks, VoIP is a no go so voice service must fall back to good old circuit switched telephony. So apart from the question of how VoIP will be done on LTE handsets the much bigger question is how to make the experience seamless over 2G, 3G and LTE.
Sure, there is Voice Call Continuity and the IMS can be configured to forward an incoming call via a circuit switched connection when no suitable wireless IP network is available. However, from what I can see so far it seems that achieving this is much more difficult then rolling out LTE in the first place.
Another alternative would be for a LTE handset to be simultaneously attached to a LTE network for data and a 2G or 3G network for circuit switched voice. This way the telephony application on the handset could be simple. Not sure if that will work in practice though!?