IP TELEPHONY.

The article presents information related to the Internet protocol (IP) telephony. IP telephony systems are designed to transmit packetized voice using the Internet Protocol (IP). IP telephony networks can offer video, high-quality audio, and directory services, in addition to services traditionally offered by the public switched telephone network (PSTN). Enterprises implement IP telephony networks to avoid the cost of supporting both a circuit switched network and a data network. Individual users save money by using IP telephony software to bypass long distance charges in the PSTN. IP telephony makes use of statistical multiplexing and voice compression to support increased efficiency over circuit-switched networks. However, many IP networks do not support quality-of-service guarantees.