[cisco-voip] SIP to Legacy PBX

[Rupert Finnigan]

Hi All,

First time poster here, so hello - and thanks in advance for any insight and
advice you can offer now and in the future.

I've been working with Cisco equipment for a while now, but have never
touched on the VoIP field - however I now have a specific interest which I
haven't been able to gather an answer to dispite my best Google-ing efforts.

We've currently got a Nortel BCM 400 system, contected to PSTN via a ISDN30
with 20 channels. I'm looking to consolodate all our conectivity to a 10MB
Fibre Leased Line from BT, and route our calls over this connection using
SIP either directly to BT, or to an alternative provider, such as Gradwell.
However.... our BCM maintenance company won't support SIP directly on the
BCM. Apparently, although the BCM will do SIP Nortel won't support it and so
it'll leave the Maintenance guys exposed should problems arise. Changing the
PBX isn't an option.

Therefore, I'm looking into the possibilty of using one of our Cisco 2821
routers to act as a SIP gateway. It'll provide the BCM with a ISDN 30 PRI,
in much the same way as it gets now to remove the Nortel support problems.
The other side will be SIP down the 10Mb line to our call provider. And
hopefully, some magic will happen in the middle on the 2821 to make this all
work "seemlessly"....

Couple of questions really - 1) is it possible, & 2) if it is, can anyone
point me in the direction of the recommended reading so I can enlighten
myself futher?

I really appreciate any help.

Thanks,

Rupes
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