Alan Percy, Director of Market Development at AudioCodes spent some time telling the audience in Dallas, Texas at this Broadvox event about how resellers can be successful at selling PBX replacements to customers. Some risks discussed were a misconfiguration of network equipment at the customer prem (keep the IT guys away from the firewall he said half-jokingly) and a cut wire underground. A solution was to keep some of the PSTN lines connected to the PBX which can get expensive. Alternatively he said you could use the AudioCodes drop and insert architecture. In this manner you can insert a Mediant 1000 Media Gateway with SIP trunking connected to it. The routing tables can be used to move from the PSTN to SIP trunking in a piecemeal way. In this manner, if the internet is lost, the proxy can route traffic to TDM and vice versa.