Cellular Network Infrastructure » Core Network (CN) » OsmoMSC

OsmoMSC rejects an Emergency Call with IMEI as mobile identity with "semantically incorrect message" which is clearly wrong. According to TS 24.008 4.5.1.5 we should reject with cause 5 "IMEI not accepted":

Normally, the mobile station will be identified by an IMSI or a TMSI. However, if none of these
identifiers is available in the mobile station, then the mobile station shall use the IMEI for identification
purposes. The network may in that case reject the request by returning a CM SERVICE REJECT message
with reject cause: #5 "IMEI not accepted".