A service is provided through an apparatus operative under Internet Protocol (IP) as part of the Internet to handle packet switched voice traffic according to Session Initiation Protocol (SIP) to control incoming packet switched control traffic by fielding SIP control traffic and substituting control signals that can traverse a firewall and handle Network Access Traversal (NAT) over an Internet Protocol (IP) network. To this end, a client behind a firewall initiates an outbound multimedia stream via a conventional voice path according to the Realtime Transport Protocol (RTP) to a SIP gateway, which in turn routes voice traffic via the Internet to the client using an XML interface to bypass the SIP-designated ports. The interface bridges the firewall and is supported by a server on the Internet that handles conventional SIP UDP interface traffic.