The method comprises: A) the external data network server sends the request message for enabling the network side carrying mobile phone number to the gateway GPRS supporting node; B) based on the mobile phone number, the gateway GPRS supporting node gets the attached registration route message of mobile user of the message at the serving GPRS supporting node; C) base on the route message the gateway GPRS supporting node allocates the dynamical IP address for the mobile user, and sends the response message of network side enabling to the external data network server. The invention can let the external data network directly initiate a network side enabling process through users mobile phone number. |