Signaling for Mobile Internet Telephony

Abstract

Internet telephony realizes the transmission of two-way, real-time, synchronous traffic over IP-based networks. The dominant standard for Internet telephony is ITU-T Rec.H.323. The current version of H.323 allows interoperability with circuit-switch telephone, but IP telephone mobility is not supported. In this paper, mobile extensions to H.323 that enable mobile IP telephony, particularly in connection with roaming and with the consideration of firewall issues, are proposed. The system architecture is described and signaling functions for mobility management are presented. We will demonstrate an approach that, through the inter-Gatekeeper cooperative support, ensures mobile IPtel services to work smoothly even with the existence of firewalls.