© 2007 AT&T Knowledge Ventures. All rights reserved. AT&T and the AT&T logo are trademarks of AT&T Knowledge Ventures. Interconnection and Interoperability in a VOIP World Challenges facing the industry Richard N. Clarke Assistant Vice President Regulatory Planning and Policy Committee on Telecommunications NARUC – Winter Committee Meetings Washington, DC 19-Feb-08
Page 2 Overview of the issues Currently, default for voice traffic exchange is TDM/SS7 Technology is very reliable and interoperable Operational systems are highly developed Business/financial models are reasonably well-known IP-originated voice traffic is expanding rapidly In the future, default for voice traffic exchange is likely to evolve to IP/SIP technology BUT EXACT ARCHITECTURES ARE STILL UNCLEAR
Page 3 Current TDM-TDM call flow Tandem Orig Class 5 Originating phone Call Direction Terminating phone Tandem Term Class 5 LERG TDM protocol transport links Analog/TDM access lines Circuit switch with routing table (simple) LERG STP SS7 protocol signaling links Signal transfer point
Page 4 Future VoIP call flows Originating Computer Terminating Computer IP protocol transport links Analog inside wire Infrastructure-Based Orig Softswitch Term Softswitch IP-IP network interconnection (peering or transit) SIP signaling packets ENUM Electronic number mapping database (complex) Peer-to-Peer
Page 5 Transition challenges Full transition to IP-based VoIP interconnection still requires: Technology to be standardized Reliability to be proven Operational systems developed and disseminated Business/financial models become clearer VoIP regulatory mandates seem unlikely to be needed 20,000+ IP networks already interconnect for best-effort data traffic exchange on an unregulated contractual basis Negotiated prices for such IP data exchange are very cheap Until IP transition progresses more fully, TDM interconnection must be the “lingua franca”
Page 6 Current VoIP-TDM call flow SIP signaling packets Originating Computer Call Direction Terminating Phone TDM protocol transport links IP protocol transport links Orig Softswitch SS7 protocol signaling links Tandem Term Class 5 STP LERG Gateway translating IP/SIP into TDM/SS7 LERG IP-TDM Gateway STP LERG