SIP g.711 a-law encoding/decoding

We need to read analog input and encode the audio stream as g.711 a-law. And also decode the incoming (from tcp/ip) g.711 a-law encoded audio stream and output this as analog audio.

Anyone heard of modules that can handle this - or perhaps even better, can this be doable on the CPU in software, and still be able to have a little resources left for other stuff? We’re planning on using the FEZ Raptor as our platform.