A CableLabs VOIP peering RFI (request for information) has been answered by many of the best-known names in the VOIP peering business, among them VeriSign Inc. (Nasdaq: VRSN), XConnect Global Networks Ltd. , Arbinet-thexchange Inc. (Nasdaq: ARBX), Neustar Inc. (NYSE: NSR), Stealth Communications Inc. , and InfiniRoute Networks Inc. , Light Reading has learned.

CableLabs, a consortium of most of the big cable MSOs, is helping its members build a VOIP peering solution that would enable direct calls between the member companies' VOIP subscribers. These calls wouldn't traverse the public switched telephone network (PSTN), a trick that could save the cable companies thousands, possibly tens of thousands, every month in interconnection fees to telcos, sources say. (See Cable Is the Voice of VOIP.)

CableLabs also points out that the quality of PSTN-connected calls suffers, because the calls often must be transcoded several times before reaching their destination. In its RFI, the consortium says videophone calls that work nicely over a direct, peered connection between cable VOIP users are reduced to audio-only when they must traverse the PSTN. (See VOIP Keeps Fueling Cable Growth.)

The RFI was issued November 22, and the due date for responses was December 14. CableLabs has said that 30 companies responded to the RFI, but it won't say what or when its next steps might be. “I think CableLabs has asked some very broad questions, and has stated very clearly that this is not even necessarily a precursor to a contract coming out,” says Arbinet-thexchange Inc. (Nasdaq: ARBX) CTO Steve Heap. “What I think they’ll do next is look at all the responses and then enter into discussions with a select group of those responders because their ideas or approaches were interesting to them.”

Stealth Communications Inc. CEO Shrihari Pandit says each CableLabs member company will choose its own VOIP peering contractor, but each winning contractor must comply with a set of standards developed by CableLabs. The creation of that standards set, Shrihari suggests, is the main reason for the RFI.The RFI itself states: “The MSO VoIP Peering project is a CableLabs-led initiative aimed at developing technical requirements, architecture and interoperable protocol specifications for delivering end-to-end VoIP and other real-time multimedia communication exchanges between service operators.” (See CableLabs Issues VOIP RFI.)

“When I looked at the RFI, I saw that the diagrams they are using look a lot like the VPF,” Shrihari says, referring to his company’s Ethernet-based Voice Peering Fabric exchange.

VOIP peering has become an important issue to cable MSOs as the number of their VOIP subscribers has swelled over the past two years. TeleGeography Inc. finds that cable MSOs are the largest providers of VOIP service in the U.S. with roughly 1.8 million users. (See Cable Gets a Vault from VOIP.)

And interest in VOIP peering appears to be growing at a pace with those numbers. "The combination of VOIP and Ethernet, is driving the VOIP peering revolution for carriers and enterprises worldwide,” writes Hunter Newby of Telx Group Inc. in his VOIP Peering report on Light Reading.

“The addition of two supporting technologies -- electronic number mapping (ENUM) and session initiation protocol (SIP) -- enables true end-to-end IP-based calling, over the public Internet or a private network, eliminating the need for an intervening carrier," Newby writes. (See SIP Guide.)

ENUM is a protocol that associates IP addresses to telephone numbers, allowing calls to be routed and managed in the IP domain from start to finish.

Multilateral VOIP peering between cable networks would eliminate interconnections with IXCs, “taking calls from the end-user device on a local network directly to another end user on a different local network by connecting the two local networks,” Newby notes.

When asked who the likely respondents to the CableLabs RFI are, Newby replied: “The usual VOIP peering suspects... as well as some carriers like Level 3 Communications Inc. (NYSE: LVLT) and, interestingly, some hardware vendors. Newport Networks plc (London: NNG) was one -- they make session border controllers.”

Representatives from CableLabs members Cablevision Systems Corp. (NYSE: CVC), Adelphia Communications , and Comcast Corp. (Nasdaq: CMCSA, CMCSK) chose not to comment on the peering initiative, referring questions to CableLabs. (See Comcast's VOIP Feature Creature.)

— Mark Sullivan, Reporter, Light Reading