I've installed a UC520-16U with 10 phones at a customer. They have an ADSL connection with a Intertex IX78 modem that's sip compatible.
Outgoing calls works like a charm every time, but all incomming calls fail. My SIP provider tells me that they can't find my UC500, so incomming calls is'nt directed at all. It's the modem that get's in the way according to them.
After a long call to the modem manufactor the ask me to upgrade and try again. At this point we see increased activity in the modems sip logs and it seems that my provider is able to reach the UC500 but still no calls come's through.
Where is the problem?
I have attached both the TAC log from the UC and SIP log from the Intertex modem.
I think the first issue is your modem should not be responding to any SIP messages on its own. Is there anything you can set on the modem to disable SIP lookup and just allow transparent passthrough of the SIP messages (i.e. UDP port 5060) to the UC520 WAN IP address? No recommendation on any DSL modem - as long as it transparently passes SIP traffic through to the UC520 should work.
Couple of things that you could do:
- ensure UC520 always uses port 5060 as the source port for all SIP traffic:
- if the SP uses different source IP addresses for SIP messages to and from the UC520 - ensure you add them in per the below
I looked through the logs, and it appears that the Intertex modem is taking the request from UC500 and passing it along to the provider fine. For example, I tracked the registration of 0545577299 which was sent out by UC500 at 11:41:59. The modem creates a proxy entry for this with its own IP address and this translation works good (there is a challenge from the provider which is passed over to the UC500 and gets responded back). With this SIP REGISTER message, 0545577299 gets registered with the provider.
Later in the logs, I also noticed that the SIP provider tried to place a call to 0545577299 (at 11:43:) , however, the Intertex modem challenged this invite and sent back a 407. I don't think this is the correct procedure. The invites from the SIP provider should be passed on to the UC500 without a challenge. Can you check with the Intertex modem folks to see if this can be disabled?