SIP trunk 32 second drop

[Avalon100]

Hi All,

Got an issue with some sip trunks on an IP500 V2 9.1, outgoing calls on the sip service are fine but incoming calls drop after 32 seconds every time. Anyone see this issue before? SIP ALG has been disabled on the router but still the same.

Thanks

 

[hairlessupportmonkey]

Whats the router?

ACSS - SME
General Geek

 

[Avalon100]

its a Watchguard firewall i believe

 

[janni78]

Do a Monitor trace, something is probably wrong in the SIP setup.

"Trying is the first step to failure..." - Homer

 

[Avalon100]

from the research I have done it seems its a SIP ACK blocking issue which seems to point back to the router

 

[amriddle01]

Also seen this when internet carriers load balance on their core network mid stream *cough* Gamma *cough*, changing to a carrier that doesn't do this resolved the issue

 

[amriddle01]

I should add this isn't every call though, so more likely the router in your case

 

[hairlessupportmonkey]

It sounds more like a NAT session closing.

You only need port 5060 open for the inbound SIP session to be initiated for inbound calls.

Make sure on the watchguard you outbound traffic isnt being sent out a UDP-TCP proxy or a SIP ALG proxy (you mentioned SIP ALG being off on the router, but this is a firewall and not a router). right below your SIP Inbound SNAT rule, create an outbound rule specifically for the IPO and make sure it only routes over one WAN (PBR) if more than one wan is present.



ACSS - SME
General Geek

 

[hairlessupportmonkey]

BTW, is this a registered or trusted SIP trunk.

Also, make sure logging is turned on for the policies (both in and outbound) and watch what happens to the traffic. The WG will also spit out a pcap for wireshark too.

ACSS - SME
General Geek