Telephony

the making of telephone calls by digitizing the sound and transmitting it through the Internet. This is often a much cheaper alternative to conventional long-distance or international calling, but there can be delays or loss of quality when the requisite parts of the Internet are congested with heavy traffic.

Originally, Internet telephony was only possible when the people on both ends were using computers with soundcards, microphones, and special software. More recently, Internet telephony gateways have been established that allow calling from and to ordinary telephones.