The network mobility (NEMO) basic support protocol is an extension of mobile IP that enables an entire network to maintain the Internet connection when it changes its attachment point to the Internet. However, it gives rise to high overhead, loss packet and long delay on the network link when a network as a unity moves frequently. These problems should seriously affect the communications, real time sessions especially. So a new session initiation protocol (SIP)-based network mobility management scheme called SIP-NEMO is designed and proposed to settle these problems. However, this scheme can not apply to all users who especially do not support SIP. So, we bring up an extensive scheme for SIP-based mobile network in this paper to improve the services to users who are aware or unaware of SIP, and what's more, our scheme can reduce the time of handoff during the ongoing users' session. The performance analysis presented in this paper shows that our proposal offers performance advantages to existing network mobility handoff scheme.