Section: 4.7.5.1.2 GMM Common procedure initiation
Content: If the network receives a ROUTING AREA UPDATE REQUEST message containing the P-TMSI type IE, and the network does not follow the use of the most significant bit of the <LAC> to distinguish the node type as specified in 3GPP TS 23.003[ Numbering, addressing and identification ]  [10] subclause 2.8.2.2.2, the network shall use the P-TMSI type IE to determine whether the mobile identity included in the P-TMSI IE, if any, or the mobile identity used by the MS to derive a foreign TLLI (see subclause 4.7.1.4.1) is a native P-TMSI or a mapped P-TMSI. The network may initiate GMM common procedures, e.g. the GMM authentication and ciphering procedure.