Next-generation heterogeneous wireless networks provide flexibility to access IP multimedia services (IMS) anywhere at any time and with always-on connectivity in various networks. IMS service allows to include various networks to provide seamless data services and helps to reduce the delay that occurred during the handoff process. Long-term evolution (LTE) is the fastest emerging mobile communication technology in the current networking field. We proposed an interworking architecture of LTE and Worldwide Interoperability for Microwave Access (WiMAX). The key goal is to provide seamless services in heterogeneous networks. We proposed an algorithm to reduce this IMS delay using Cross-layer and Context Transfer Prior –SIP (P-SIP) scheme using...