M.5 Use of circuit switched domain

24.2293GPPIP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Release 18Stage 3TS

When an emergency call is to be set up over the CS domain, the UE shall attempt it according to the procedures described in 3GPP2 C.S0005-D [85].

Annex N (Normative):
Functions to support overlap signalling