Нашел кое какую информацию по этому вопросу в
3GPP TS 24.008Цитата
4.3.3 Identification procedure
The identification procedure is used by the network to request a mobile station to provide specific identification parameters to the network e.g. International Mobile Subscriber Identity, International Mobile Equipment Identity (see 3GPP TS 23.003 [10]). For the presentation of the IMEI, the requirements of 3GPP TS 42.009 [5] apply.
4.3.3.1 Identity request by the network
The network initiates the identification procedure by transferring an IDENTITY REQUEST message to the mobile station and starts the timer T3270. The IDENTITY REQUEST message specifies the requested identification parameters in the identity type information element.
4.3.3.2 Identification response by the mobile station
The mobile station shall be ready to respond to an IDENTITY REQUEST message at any time whilst a RR connection exists.
Upon receipt of the IDENTITY REQUEST message the mobile station sends back an IDENTITY RESPONSE message. The IDENTITY RESPONSE message contains the identification parameters as requested by the network.
Upon receipt of the IDENTITY RESPONSE the network shall stop timer T3270.
Но вопросов это как-то не убавило. Не понятно, как создать RR connection на элементарном уровне и как выглядит IDENTITY REQUEST...