[VoiceOps] AT&T Flexible Reach

[Alex Balashov]

I was thinking more of scenarios in which there is an edge 
element/administrative border which can perform header manipulations, 
particularly adding identifying headers, but can't mangle to the same 
extent that an SBC (with a B2BUA internally) can.

As a company specialising largely in proxies for such applications, 
that's something that comes up in our radar a lot.  We can debate the 
propriety of using a proxy for such an application, but regardless, it's 
commonly done, for reasons of throughput and cost.

The problem, as you know, is that proxies are quite circumscribed in the 
aspects of a SIP message they can manipulate--at least, 
standards-compliant proxies.  In a very real sense, UAs on two sides of 
a proxy are interoperating with each other, rather than with the proxy. 
  This creates both philosophical questions ("what exactly is the CPE 
here?") and a orthogonal, sometimes turbulent approach in relation to 
Bellhead expectations about how trunking works.

-- 
Alex Balashov - Principal
Evariste Systems LLC
235 E Ponce de Leon Ave
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Decatur, GA 30030
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