Section: 6.4 MSISDN notification procedure
Content: The MSISDN notification procedure allows the MS to query the network for its MSISDN for the purpose of user information. In order to request the MSISDN, the MS shall encode the protocol configuration options information element (subclause 10.5.6.3) in the MS to network direction to indicate MSISDN query. The network shall then provide the MSISDN, if available, in the protocol configuration options information element in the network to MS direction. Querying the network and handling of the provided MSISDN by the MS is implementation dependent, in a similar way to the USSD notification or application mode defined in 3GPP TS 23.090[ Unstructured Supplementary Service Data (USSD); Stage 2 ]  [132]. NOTE: The MS might store the provided MSISDN in the corresponding USIM file (see 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [112] subclause 4.2.26) and such an MS could check this USIM file to determine whether to query the network. The network shall provide only one MSISDN. As a result, a provided MSISDN shall supercede any MSISDN that was previously provided in the protocol configuration options information element. The MSISDN provided is for user information only, and the MS shall not use the MSISDN in any NAS signalling procedure. If the MSISDN is stored in the ME, the ME shall retain the MSISDN at power off. The MSISDN stored in the ME, if any, can only be used if the IMSI from the USIM matches the IMSI stored in non-volatile memory, else the MS shall delete the MSISDN.