QUESTION: Is there some issue with Voice in LTE Release-8?
ANSWER: Yes! There is no inbuilt solution for voice (and SMS) in LTE Release-8. There are various approaches suggested. The first is the CS Fallback option. The second is the IMS option and finally the third is the VoLGA option. You can read about the first two options here and about VoLGA here.
It is also possible to use the VoIP clients like Skype for voice calls. LTE has been designed around a low latency and low jitter architecture that should easily support VoIP clients. The adoption of VoIP on LTE is going to have to overcome similar perception issues that existed with VoIP over the internet. These include:
- The perceived inefficiencies and voice quality management challenges to support a voice/media connection over a packet-switched network. RTP traffic (referred to as Unacknowledged Mode service in LTE) can be accommodated over an IP network, so long as the correct QoS policies are used, which leads to the next hurdle
- The cost of supporting RTP traffic with packet prioritization through an IP network (QoS policy) versus the diminished revenue of VoIP vs Circuit Switched telephony. This cost vs. benefit analysis is a big factor in VoIP adoption on wireless networks
- Support for the rich SS7/MAP/WIN feature sets for CS telephony over 2G & 3G networks. SIP and IMS have gone a long way towards bridging this gap and the LTE EPC is designed with carrier-class VoIP service in mind. Regardless, this is a bit of a perception issue with many operators.
It is quite likely that some operators will launch LTE with VoIP and others will launch LTE as a high-speed data overlay for their existing 2G/3G networks, which will continue to carry CS traffic by forcing I-RAT handovers from 4G or through managing dual 2G/4G or 3G/4G connections to their subscriber's UE's.
There is another option from Nokia called "Fast track VoLTE". Since its proprietary, no one is paying much attention.
SOURCE: Solving the LTE voice dilemma - 3g4g Blog
SOURCE: VoLGA: Bringing Voice to LTE - 3g4g Blog
SOURCE: LTE: voice issue - Linkedin
SOURCE: Fast Track VoLTE - NSN