[Asterisk-Users] SIP registration behind Linksys WRT54G

[Tomas Florian]

Hello,

I'm having some major problems getting SIP phones to register whenever I put
them behind a Linksys router. The same phones will register behind any other
NAT (I've tried 3 others without problems)

I've been debugging using Ethereal and these are the differences that I
found between Linksys WRT54G and a Monowall Router as an example (Monowall
router is one of the many that work fine for me):

REGISTER sip:asterisk.mydomain.com

	Monowall (good registration)

	- Via: SIP/2.0/UDP 192.168.10.199;branch=...
	- Authorization: DIGEST ..., uri="sip:asterisk.mydomain.com", ...
	- Contact <sip: 204 at 192.168.10.199;user=phone>

	Linksys WRT54G (Bad registration - 403 Forbidden)
	
	- Via: SIP/2.0/UDP 66.x.x.166;branch=...
	- Authorization: DIGEST ..., uri="sip 66.x.x.166:5060", ...
	- Contact *


As you can see the difference seems to be that with the Linksys the SIP
request has it's WAN IP + port (66.x.x.166) whereas the request from behind
a monowall has the LAN IP of the phone 

What is the explanation for this difference?  Needless to say - I don't have
any special port forwarding enabled on either one of these routers and I'm
using the identical phone with identical configuration for both tests.

I have outgoing proxy in my phone's configuration but it almost looks like
it's disregarding that option when behind the Linksys router.  

Another interesting thing to note is that I have tried connecting to some
other proxy from behind Linksys (not my own asterisk but some other provider
- I don't know what they are running)  I was able to register without a
problem.  Interestingly, the registration request looked identical to the
monowall one (Via: LocalIP , uri: FQDN ) ... unfortunately because I am not
the system admin on that VoIP server I can't login to see what configuration
they have in order to copy it.

I'm really out of ideas ... if anyone has any hints of what else I could
check out I would really appreciate that.

Thank you,
Tomas