Monday, October 24, 2005

Private ENUM Trees and VoiP Peering Exchanges popping up like mushrooms 

After and XConnect, and of course GSMA's GRX together with Neustar, and some other more hidden ones, today two new ones joined the club. I wanted to post the links to the press releases distributed via the VoIP Peering list mentioned below, but Irwin Lazar did the job already: VoIP Peering Comes of Age?

(Note: see also Rich Tehrani's recent post: Where is VoIP Peering headed?)

Rich Tehrani has proclaimed that 2006 will be the "Year of VoIP Peering", it looks like he may not have to wait until 2006 to see a huge jump in efforts to directly link VoIP networks together.

Neustar, best known for managing the PSTN number database, has announced a new join effort with Equinix, TELEHOUSE, and the Amsterdam Internet Exchange to build a SIP-based peering exchange.

In addition, Sphere Communications and BroadSoft announced today at IT Expo an agreement to enable Sphere's customers to directly peer via SIP with providers running BroadSoft's call management platform. Finally, FiberNet announced today a new "carrier-grade platform for VoIP" peering. FiberNet will host its peering point in NYC.

About a year ago or so my colleague Dan Golding set up a mailing list for the discussion of VoIP peering. After a brief initial burst of activity, the list has been almost dormant for the last six months or so. I think that's about to change. (To subscribe, send a message to "" with "subscribe" in the message body, an archive is available as well at")

All these announcements show a growing level of interest in VoIP peering, and with it perhaps the next phase of IP communications is rapidly approaching, where VoIP-to-VoIP calls replace PSTN trunks, offering significant potential for lower costs, as well as the opportunity to piggy-back additional services such as instant messaging and presence.

I just wonder how many of these ENUM trees and IXchanges will pop-up in the future and why one needs a SIP proxy to do the exchange. The basic idea with SIP is that one can reach any other VoIP proxy given the SIP URI (Address-of-Record). I hope the "exchanges" only exchange SIP signalling and not media streams, because this would re-create the PSTN and its transit networks. But what is the reason for a signalling transit?


Trust can also be established via other means, e.g. with certificates.

So what is left is E.164 number mapping to SIP URIs. For the ones new here, this is called ENUM.

The IETF ENUM workgroup is in this moment extending its scope to include public carrier or infrastructure ENUM to provide E.164 number to URI mapping for carriers-of-records.

In parallel IETF is trying to set up an additional WG to define VoIP Peering. Stay tuned in approx. 3 weeks whats happening here at the next IETF in Vancouver.

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