[c-nsp] SIP problems with 1721

[Andreas Sikkema]

Hi,

I'm working for a VoIP providerin Holland. We've got a customer with a
Cisco 1721 router running software which the customer calls 12.2
(Unfortunately I don't know anything more, they apparently know on know
how to configure some simple things).

Behind their router is a NATted SIP device which is trying to make calls
using our servers. Unfortunately the router understands the SIP
protocol, and tries to solve the NAT problem it thinks there is by
changing the IP addresses. I think there's a bug in the software because
it corrupts the SIP message.

Is there a known problem? Is there an easy way to shut down the SIP
"helper"? We've been looking for info on the Cisco site, but couldn't
find anything. 

-- 
Andreas Sikkema