Abstract: An Internet Protocol (IP)-based radio telecommunications network and method of providing data services to a mobile terminal. An Internet Protocol Shared Interworking Function (IP-SIWF) is implemented in the network, and is controlled from a Mobile Switching Center (MSC) utilizing the Media Gateway Control Protocol (MGCP) device control protocol. When a data call carrying a data payload is originated by a mobile terminal, the data call is transported utilizing radio access and radio link protocols to the IP-SIWF. The radio access and radio link protocols are terminated in the IP-SIWF, and the data payload is transported thereafter utilizing a real time protocol over a User Datagram Protocol (UDP) and an IP protocol layer.