atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems DT700 loses connection to SIP server over VPN

HI All,

I am getting more and more frustrated and am hoping someone can help. DT700 12 and 24 Button connecting to SV8100 via IPSec VPN. Handset registers fine, but loses connection after a while ( Ranging from 10 Minutes to 8 Hours).

I ran a Wireshark trace and found that handsets at the remote sites tend to re-register with the SIP server at varying intervals. Occasionally a registration request will get a "Status: 401 Unauthorised" response from the SV8100, and that's that. To connect again, reset handset to Factory default and reconfigure with IP, Gateway, Subnet, Sip server address and port. Phone reconnects and problem re-occurs.

I found in the wireshark trace that the handset identifies it self as ext# @ IP address : Port. i.e. [email protected]:5060. receives Status: 200 OK.

At other times the handset ID is necsipuser @ IPLA IP address: port.
i.e. [email protected]:5081. This request is then refused. Status 401: Unautorised and Phone displays, SIP SERVER not found.

I can still ping the IPLA from the handset and can access phone setup via web browser, but handset will not register and subscribe to SIP server.

Anybody seen this before or any ideas how to get around this. I have upped Keep alive values 84-15-03/04 with no difference.

Thank You in advance.

Jahn

Are you sure the VPN tunnel isn't going down at some point?

maybe changing the ports 5080 and 5081 to a different port.

HI Guys,

Thanks for the feedback. No, VPN tunnel stays up, got a Shoretel system connected via the same VPN and it stays up. Tried changing the ports with the same result. Will keep trying and really appreciate the suggestions.

You might try the latest sw. upgrade if available in your area. 6.02 is supposed to have addressed some IP issues

We do not have access to 6.02 yet, but I have upgraded to V.6 with no change. Thanks anyway, I am waiting to hear back from the local NEC office regarding availability of 6.02. Really doubt it will work, but at this stage I'll try anything.

Don't hold your breath for 6.02 this side of Easter..

OK, seem to have this sorted. For anyone having a similar problem; Disable SIP ALG in the routers. Job done. Simple right????

Yep. Had that at home when I change ADSL routers with my IP fone. SIP ALG is usually turned on by default. Same applies if you are using SIP trunks over ADSL..