The present invention is directed to a mobility management protocol for supporting real-time and non-real-time multimedia applications on mobile stations of third generation internet protocol (3G-IP) networks. The present invention utilizes as well as extends the session initiation protocol (SIP) to provide for domain hand-off (i.e., roaming) and subnet hand-off (i.e., macro-mobility) so that users can access the network from any location using their own mobile station as they roam across different 3G-IP networks. The present invention supports mobile transmission control protocol (TCP) applications without modifying TCP. More specifically, disclosed herein is: a novel use of the SIP INVITE method for IP address binding; a novel use of the SIP INFO method to provide a means of profile verification and IP address binding; a novel use of the SIP REGISTER method to allow a SIP registrar to obtain a new IP address from a Dynamic Host Configuration Protocol (DHCP) server on behalf of the mobile; and an inventive entity called a SIP_EYE Agent that maintains a record of ongoing TCP connections and releases within the mobile.