How to troubleshoot sip connection to polycom phone?

An offsite phone worked fine in one location, taken to a different state it wont register with sip. It connects to the PBX with ftp at an address, so how come sip wont connect at that same address.

How can the point of trouble be found ?

What in the asterisk Cli can by typed that will indicate why the darn thing is refusing to register ?

sip.conf

[183]
type=friend
username=183
mailbox=183
context=from-sip
secret=itsasecret
host=dynamic
qualify=yes
nat=yes
call-limit=8

Hi

You need to sniff the interface its connecting to and then debug it in wireshark. This will show you whats going on.

Ian