METHOD OF CALL SETUP TIME REDUCTION FOR VOICE OVER LTE

摘要

Methods and apparatus are provided for a voice over LTE system to shorten the call set up time. In one novel aspect, the mobile origination (MO) UE starts the UE-initiated dedicated resource allocation before receiving any responses from the remote UE. In another embodiment, the mobile termination (MT) UE starts the UE-initiated dedicated resource allocation upon receiving the INVITE from the remote UE. In one embodiment, the UE adjusts the timeout value based on the PLMN information in its PLMN database. The timeout value can be set to be zero if early reservation is allowed. Upon timer expires, the UE starts UE-initiated dedicated resource allocation. In one novel aspect, the MO UE retrieves the codec information of a remote UE from its peer profile information database and uses a matching codec in its INVITE message. In another embodiment, the MT MO includes the SDP answer in its 180 RINGING message.