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
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
ï¿½- 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
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].
ï¿½- Jeff Paine, vice president of marketing, Syndeo Corporation
To The May 2001 Table Of Contents ]