In one embodiment, a method for processing, at an enhanced Session Initiation Protocol (SIP) proxy (e-proxy), (1) a SIP INVITE message to a first user at an IPv4/IPv6 dual-stack (DS) host, connected to an IPv6 network, from a second user at an IPv4 host, connected to an IPv4 network. The e-proxy receives the SIP INVITE message from the IPv4 network. When the e-proxy determines that Dual Stack Transition Mechanism (DSTM) service is required, the e-proxy obtains a temporary IPv4 address for the DS host, finds a suitable tunnel end-point (TEP), and sends a corresponding, but modified, INVITE message to the DS host. The modified INVITE message body includes invocation of DSTM service, the temporary IPv4 address, the TEP's IPv6 address, and the IPv4 host's IPv4 address. The e-proxy sends a BIND message to the TEP to bind the DS host's IPv6 address to the temporary IPv4 address for proper tunneling.