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Letters To The Editor
May 2001


In This Month's Mailbag

Next-Gen Broadband Architecture
I am regular reader of your magazines and I'm interested in the field of IP telephony and the next generation voice over broadband architecture. I understand quite a lot about softswitches, media gateways, IP telephony protocols, etc... I have a question to ask regarding the architecture of voice over broadband solutions.

In all the descriptions of voice over broadband, the one constant mantra is that the costly CO switches (5ESS and others) shall be no longer required. The call control will be done by off the shelf computers running some fault tolerant OS (not Windoze), and they will control the media gateway (MG). The customer is going to get connected to the media gateways through on-premises IADs (integrated access devices). Apparently, the MG or MGC (media gateway controller) is going to have a link to the SS7 network to do call routing, etc... so that when a customer connected to a POTS switch calls a voice over cable customer, the calls gets routed to the correct MGC, and from there to the customer's premise.

But in a lot of diagrams illustrating this subject, I find that the media gateway is connected to the CO switch. Why should that be? I thought the whole intention was do away with the CO switches. They are the most expensive component for a CLEC. And the presence of a CO switch in the next-generation architecture signifies that the hegemony of the Baby Bells is not going to go away.

On that related front, maybe you could point me to an article that describes how a CLEC can set up voice over cable services.
�- Manoj Sati

We asked Jeff Paine of Syndeo Corporation to reply:

The author of this letter is in search of honest answers in a softswitch marketplace that is very confusing -- at times deliberately so.

The core of the disconnect that he sees comes from two places. First, his focus is on delivery of line-side services, which include both revenue-generating Class 5 services (e.g., dial tone, call waiting, caller ID...), and regulatory services (e.g., E911, legal intercept...) that are currently delivered by -- in his words -- "costly 5ESS CO switches." I fully agree that an IP-centric, softswitch-based replacement/alternative is the epitome of what the softswitch concept is all about.

The trouble is that most so-called "softswitch" vendors have addressed the tandem/trunking world of the Class 4 switch, which is all about arbitrage and cost savings. In this context the technology choices made by the traditional Class 4 softswitch players -- active/standby architectures, IP-based failover and the like -- were absolutely appropriate. But in the performance- and regulatory-edge-case-ridden world of Class 5 replacement, these architectures are simply non-starters.

The second source of the disconnect is that much of the flurry of activity in the ranks of the International Softswitch Consortium (ISC) on the services side (i.e., the SIP applications pack) has actually produced some very elegant renditions of the next-generation of enhanced service platforms -- not Class 5 replacement softswitches.

Only a few vendors, have built the Class 5 replacement softswitch, and products are just now beginning to ship. In our view, the Class 5 softswitch must be simultaneously an MGCP media gateway controller, an SS7 signaling point, a SIP proxy and redirect server, and an H.323 gatekeeper. Nothing short of full mediation of all commercially significant call control protocols for end points is acceptable in a Class 5 replacement platform.

While most media gateways will be connected to existing ILEC Class 5 CO switches for a long time to come -- to allow IP endpoints to converse with legacy POTS phones -- there are many points of light at the end of this tunnel. First, true Class 5 softswitch platforms can deliver dozens of Class services to standard phones using MGCP. Second, a number of major carriers have proposals out for solutions to "decommission" their existing Class 5s. Third, softswitch vendors are partnering with "next-generation" Class 5/media gateway vendors to let RBOCs do voice offload of their Class 5s. These solutions will be in customer trials by the end of 2001.

Syndeo offers a number of white papers that address the issues involved in deploying voice-over-cable services, including comprehensive discussions of regulatory issues; these can be obtained by sending a request to [email protected].

�- Jeff Paine, vice president of marketing, Syndeo Corporation

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