After I decided on the NEC SV 8100 PBX, the next big decision was selecting an IP trunk vendor. In this country, Internet Protocol trunks are usually called SIP trunks, after the Session Initiation Protocol that most of them use. I looked at two choices: AT&T and Appia. The AT&T solution required replacing my existing AT&T router. AT&T said that the operation couldn’t be done without running both the old and the new router in parallel, and I didn’t have enough copper pairs to make that happen. I had already dealt with Appia when I was looking at cloud solutions, so I agreed to give them a try.
The first problem occurred when the contract arrived. I needed to sign up for a year, but, since I was getting my Internet service from AT&T rather than Appia, Appia did not guarantee that anything would work. The installers had a set of test Appia SIP trunks, so I agreed to start with them, and sign a contract with Appia once I was satisfied with the results. The Appia pricing was pretty attractive: six virtual trunks, 800 countrywide minutes a month, all for less than 100 bucks a month. However, I really wanted to find out what the quality would be like; hundred bucks is no bargain for lousy reliability or voice quality.
I had the installer leave the old PBX in place, tied to its analog trunks. I signed up for call forwarding with AT&T, and programmed the trunks to unconditionally forward to the pilot number for the Appia SIP trunks. With that set up, it would be easy to go back to the old PBX if something bad happened to the new one. The installer installed all the IP phones, including two portable phones that use Wi-Fi to connect to the PBX. We programmed the calling party ID number for outgoing calls made on the Appia SIP trunks to the pilot number for the old analog trunks, so people receiving calls from the new PBX wouldn’t be confused about who was calling them.
Over the next couple of days, we found two problems with the Appia SIP trunks.
When we called some numbers from the IP phones, we would get no call progress tones (ringing, busy etc.) other numbers worked just fine. After many days of calls to the Appia tech-support line, we finally traced the problem. Calls made to numbers which gave call progress by sending back packetized audio information worked fine. Calls made to numbers which gave call progress by sending back an indication to the PBX to play call progress tone X didn’t work. Appia blamed the PBX. The PBX installers, after working several hours and spending some time on the phone with NEC tech-support, were not able to fix it.
Some calls to land lines had dropped packets from the distant party, which decreased naturalness at low incidences, and made the distant party unintelligible when a lot of packets were dropped. There seemed to be no pattern to this, but it did seem to affect quiet conversations more than louder ones.
After several weeks of not being able to fix the problems, I decided to abandon the Appia SIP trunks, and connect the analog trunks to the PBX. In a year or so, when my router needs to be replaced, I will consider AT&T SIP trunks.
A few days after I decided to drop Appia, but before I could do anything about it, all incoming calls started to receive a fast busy signal. Outgoing calls worked, but showed a number I’d never heard of in the calling party ID field. A week’s worth of troubleshooting with Appia proved fruitless; they said it was a PBX problem, but we couldn’t find anything that had changed on the PBX. These problems made me really glad I was dropping Appia. I took the call forwarding off the old analog trunks and went back to using to old PBX while I waited for the installers to switch the analog trunks to the new PBX.