LTE: How SMS services will be received in LTE network ?

Question

If a UE is connected to LTE network, can it receive SMS services too ? If yes then how it can be achieved ? How the signalling or SMS messages will flow between UE and Network ?

Answer 1

Hi rupam,

SMS and voice is mostly not implemented in LTE network. We know IMS is the one solution to handle voice and SMS, but to have IMS both network operator and UE has to support. So they introduced kind of CS fallback to handle SMS. For voice we know UE will fall back to CS network to recieve voice. For SMS UE will construct NAS ultransfer message and append the SMS data in it, then forwards to MME. Then MME gives that message to MSC then to actual destiantion. In DL SMS MSC will send SMS data to MME ,then MME constructs NAS DL-info transfer with SMS data then sends to UE thrugh ENB.