How do I do TCP/IP dump

I am using the FreePBX Distro, I am at 1.810.210.57-1. I have multiple service providers. I am getting intermittant congestion with one of my carriers and looked in my Asterisk Log and see that this seems to be the relevant line:
[2012-05-29 13:55:35] VERBOSE[3917] chan_sip.c: – Got SIP response 503 “Service Unavailable” back from
I called my service provider and they want a tcpip dump, and I say I do not understand how to do that, and they act as though I ought to know and as if it is obvious. So my question is

  1. Is it possible that the problem is on my end or am I simply getting congestion from my SIP provider?
  2. How can I give them what they want, (a tcp IP dump)?

You are getting the message back from so if that is your carrier they are sending the message.

You can dump SIP messages from that peer (or any peer) with ‘sip set debug ip’ , make sure to turn it off when you are done with ‘sip set debug off’

Also you want to turn off the dial plan messages so they don’t clog the log while you are capturing the SIP messages, use ‘core set verbose’ 0 and ‘core set debug 0’

The log gets written to /var/log/asterisk/full

These are all asterisk commands.

For the full suite of sip commands look in the Asterisk SIP documentation.