Some organisations have already made huge investments in legacy PBX phone systems.  But they still want the benefits that come through converging all local and long distance phones systems and broadband Internet services onto one line.  SIP Trunking allows businesses to reap VoIP-like benefits with legacy systems, without investing in new infrastructure.  Using SIP, you can consolidate all your communication systems, including data and voice into one bill and a single point of contact.