While SIP Trunking continues to be one of the hottest topics in today’s evolving telecommunications marketplace, there is another application in this same space that is often overlooked: Connecting an IP-PBX or other VoIP Communications Platform back to the PSTN. There are many reasons why an enterprise may want this kind of legacy connectivity, such as: access to emergency response, resilience in the event of a WAN or ITSP failure, operating equipment that does not run reliably over a VoIP network (e.g. fax servers, modems, alarm systems) and regulatory compliance.