[Asterisk-Users] Registration failed problems/Polycom 500/maybe nat problem?

[Chris Mason (Lists)]

I have sent a Polycom IP500 phone to an overseas remote user who has a 
Speedtouch adsl modem/router. The phone is connected to the 4 port 
router which performs NAT for the network.
The phone rboots, find the server, downloads it's config and tried to 
register. Then it immediately becomes UNREACHABLE.

Jul 26 17:44:41 NOTICE[21026]: chan_sip.c:9138 handle_request_register: 
Registration from '<sip:816 at 207.44.xxx.xxx>' failed for '209.59.xxx.xxx'

816/816                    209.59.xxx.xxx     D   N      
255.255.255.255  10979    UNREACHABLE

I have tried everything I can think of. Is it possible the ISP is 
blocking the SIP packets going back to the phone?

The entry in sip.conf is:
[816]
type=friend
host=dynamic
dtmfmode=rfc2833
username=816
secret=mysecret
canreinvite=no
callerid="Me" <816>
mailbox=816
disallow=all
allow=g729
allow=ulaw
nat=yes
qualify=yes
context=default

-- 
Chris Mason
NetConcepts
(264) 497-5670 Fax: (264) 497-8463
Int:  (305) 704-7249 Fax: (815)301-9759 
Cell: 264-235-5670
Yahoo IM: netconcepts_anguilla at yahoo.com