Let us see how the analog voice is digitized and combined with the rest of the data and the functions of Telephone signalling etc.
![Phoneint](http://www.ncra.tifr.res.in/ncra/gmrt/sub-systems/monitor-control/voice-communication/phoneint.gif/@@images/7e23eb45-973b-469f-a746-546cdb77e4a3.jpeg)
INTEL 29C17 CODEC IC has been used for digitizing voice using 7.8 KHz clock and it produces 62.5 Kbits/sec rate.The CODEC uses "A law " for data companding\expanding.