Study, on robust billing mechanism for SIP-based internet telephony services

Nowadays, there are many Internet telephony services that support IP-IP telephony, IP-PSTN telephony or something like that. The most significant changes in Internet Telephony filed are appearance and increasing expansion of SIP protocol instead of H.323. Because H.323 protocol is TCP-based protocol, billing is so easy. However SIP protocol is UDP-friendly protocol that may cause problem with signaling loss due to the unreliability of UDP datagram. In this paper, we categorize the billing method and suggest robust billing method for SIP-based Internet Telephony.