Section: 19.3 Mz messages
Content: This clause defines the Mz interface Diameter messages. The Diameter messages used in the Mz protocol, are the same as specified for Gmb interface described in Clause 17 of the present specification: AAR Command (clause 17.6.1), AAA Command (clause 17.6.2), STR Command (clause 17.6.3), STA Command (clause 17.6.4), Abort-Session-Request Command (clause 17.6.7) and Abort-Session-Answer Command (17.6.8). To route Diameter messages from the visited PLMN to the home PLMN, the BM-SC in the visited PLMN shall derive the realm of the home PLMN from the user’s IMSI. The way to derive the realm of the home PLMN from IMSI is specified in 3GPP TS 23.003[ Numbering, addressing and identification ]  [40] subclause 15.4. The derived realm of the home PLMN shall be filled in the Destination-Realm AVP of messages sent from the visited PLMN to the home PLMN, i.e. AAR command, STR command.