[VoiceOps] The peer of my peer is my peer?

Alex Balashov abalashov at evaristesys.com
Tue Jul 13 18:42:12 EDT 2010

On 07/13/2010 05:35 PM, Kristian Kielhofner wrote:

> I've seen this happen with resellers that only use a proxy between
> their customers (Bandwidth.com).  In that case all transport, codec,
> and caller ID parameters must be compatible (Bandwidth won't do
> anything about them).

It's even worse if the end-users behind the ITSP's proxy are behind NAT. 
  You can do signaling-level NAT fixups in a proxy, but without relaying 
media, you rely on the upstream carrier's edge equipment to do 
draft-comedia style NAT traversal on the media, whereupon the true UDP 
source port of the RTP is discovered prior to sending RTP to the 
end-user leg (on the assumption of symmetric RTP), instead of using the 
UDP port declared in the SDP body coming from the end-user.

Bandwidth.com's edge equipment does not do such fixups, so it is 
entirely incumbent upon the ITSP to deal with this situation.

> With Level(3) Vector they hold media and can make codecs compatible.
> However, one problem we have found is Caller ID presentation.  When
> going to a peer Level(3) will not do a dip and set the from name, they
> depend on the originating network to set the CID appropriately or they
> depend on the terminating network to do a dip.

... in E.164, no less.

Alex Balashov - Principal
Evariste Systems LLC
1170 Peachtree Street
12th Floor, Suite 1200
Atlanta, GA 30309
Tel: +1-678-954-0670
Fax: +1-404-961-1892
Web: http://www.evaristesys.com/

More information about the VoiceOps mailing list