With LTE, voice calls
are no more much toilsome to be made. Only packet switching is supported by the
LTE standard in association with its all-IP network. GSM, UMTS and CDMA2000 voice
calls are all circuit switched. It means that carriers are in need of
re-engineering the network for their voice call if they work with the adoption
of LTE standard. With the passage of time different approaches have been taken
and it is three in number.
VoLTE is an approach which
is based on the Subsystem network of IP Multimedia. VoLTE stands for Voice Over
LTE is an approach having specific profiles for control and media planes of LTE’s
voice service which GSMA has defined in PRD IR.92. Voice service is the outcome
of this approachthat is being delivered within the bearer of LTE data. It has
reduced dependency on the voice network of legacy Circuit Switch. It ultimately
means that there is no requirement to maintain any legacy circuit switch.
CSFB is another
approach which allows LTE to provide only data services. When at the time of
making or receiving a voice call, the call will automatically fall back to the
CS domain. So, CSFB means Circuit Switched Fallback. When the operators intend
to use this solution, they will have to upgrade or develop the MSC in lieu of
employing the IMS. In this way, they can easily provide services as quickly as
possible. Despite the advantage, there is a disadvantage too and it is the
delay for setting up longer calls.
Another great approach
is SVLTE that stands for Simultaneous Voice and LTE. This good approach allows
the handset to work effectively both in the LTE and CS modes. The approach
works with the LTE mode by dint of data service supply, However it works with
the CS mode by providing the voice service.
