Common Causes for Multisite Interconnect Call Failure


PBX version: all


1. Connection failure between HQ and Branch site caused by port mapping error

Symptom: Connection between headquarter and branch side can't be established.


1) Check the network connection between HQ and branch site by the Ping tool.

(go to Maintenance>IP Ping)

2) Check the SIP NAT setting on web (HQ site) and make sure the port 5060 has been mapped (HQ site) on your router. You could use a remote extension to attest if the port mapping and NAT take effect. If remote extension registration fail, try to check the network environment with your IT guys plz.


2. Firewall block 

Symptom: Call from HQ to Branch site could work, but Branch to HQ failure or opposing situation.

Solution: Remove the IP address in IP Auto Defense list on HQ/Branch site.


3. Superfluous SIP trunk between HQ and Branch site

Symptom: Call from HQ to Branch site could work and vice verse, but Branch can't call Branch.

Solution: Delete the SIP trunks between HQ and Branch site. Generally you could only choose one interconnection method (SIP peer trunk/ Multisite Interconnection feature) at the same time.


4.  Connection status is judged as unreachable because of the unanswered "OPTIONS" message

Symptom: Connection between HQ and Branch is not stable.

Solution: Try to disable the Qualify option on both Branch and HQ site. 

Note: As when you enable the "Qualify", PBX will send "OPIONS" message to verify if end-point still alive at a short interval. Try to disable the "Qualify", then System will not send the message any more.

What if the issue still persist?

Please help get the pcap dump on both HQ and branch sites simultaneously followed by this link: 

Then send us the pcap dump. 

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