A mobile telephone network has a function (30) which interacts with the platform (40) or platforms processing a call, event or session to: a) determine the services and/or call handling operations to be applied to the call, event or session; and b) determine if the platform(s) (40) are capable of carrying out the services and/or call handling operations required by the call, event or session. The function may then arrange for the platform (40) to be provided with appropriate data or for the call, event or session to be transferred to another platform. Moreover, a call may have part of its data converted into a standard protocol, and the data in that standard protocol then be used to guarantee a trigger for processing the call at a transfer device.