Registering an enterprise-associated mobile device with a private branch exchange

The application relates to communication systems comprising a Private Branch eXchange PBX (16) and a platform which performs some aspects of messaging or session control, like call control and advanced call processing features and in some cases, also performs some media handling. This platform is referred to as "Service Management Platform" SMP (18) and is connected to the PBX via either a PRI connection or a LAN employing protocols like SIP, ECMA-269, ECMA-232. Each user has an account comprising information such as his enterprise extension. The account information might not comprise the communication path of a user device. The communication path comprises a PBX system port. In order to record the PBX which is handling calls from the user device, the SMP is configured to direct the mobile communication device associated with the enterprise account to call a configuration telephone number which routes call control to the SMP (632,634). From this call (643), the SMP determines the PBX system port of the call and records it in the account information such that the account information provides a mapping between the account, the extension, and the PBX system port.