Asterisk is the Open Source PBX software that can manage telephone lines. As well as the classical hardware phones, more importantly for me, it also manages VOIP traffic. I decided to give it a go after I received our last quarterly telephone bill and discovered that we had spent £110 talking to my daughter in the period.
An initial trial last week managed to allow my daughter to call in from outside and have a voice conversation with me (who was inside the house). This is with two firewalls (one at her place and one at mine) in the path. Unfortunately, there was a problem with my microphone.
Over the weekend I extended that further, connecting the Free World Dialup and used there echo service to take a call and bounce it back to me.
I have also ordered a linksys SPA3102 so that I can try and connect a real phone into the process.
I was worried that yet another application running on my server would bog it down, but it doesn’t appear to be a problem with CPU load rising from an average of around 2% to about 5% when asterisk is bridging a call including changing codecs (and therefore presumable de-encoding and then re-encoding the voice on the channel).
I still have a problem with sound quality but it seens to get better with every tweak that I do. Lets hope over the next week I can get it working fully.