VoIP Voice compression, How to Prgoram

I’m planning to make a layer seven application compliant with H.323 CISCO standard for Voice Over IP. Means I’v to grab the voice from Microfone, compress is and transmit as packets. Any suggessions
* Whic language to use
* What compression technique to deply (wavelets?)
* What constraints

I mean, is there anybody who’s already worked on this? Please help me out
thanx