VoIP (Voice over IP) is starting to feature as a means for telcos to pass traffic between each other, as well as to/from customers. VoIP is a way of passing voice and fax calls over data circuits using the Internet Protocol (IP). With the ever increasing capacity of these data circuits, VoIP has become a viable means of moving telephone traffic between users.
VoIP itself can be encoded in a number of ways, but the most popular are SIP (Session Initiation Protocol) and H.232. Tuxtel uses SIP to encode its voice traffic over data circuits.