atcomsystems.ca/forum Forums TDM Business Telephone Systems Toshiba Telephones & Systems SIP Trunk Problem!

Have a customer using an MIPU24 with 8 SIP trunks, and the rest of the MIPU slots are filled with IP phones. In house (not IP phones - although it also happens on IP phones) if a call is in progress, and someone else hangs up their phone - the person still on the phone will get 3-5 seconds of silence - neither party can hear anything.

I duplicated the problem on an IP phone on my desk (about 100 miles from the customer), made a call to my cell phone, then just tapped my cell phone so I had constant clicking - when I saw someone else hang up - I had silence both ways for about 5 seconds. So this really is the problem, exactly as the customer describes. (how rare is that!)

I'm planning to replace the processor and MIPU card, but any other ideas? Been doing Toshiba for 30 years, but this one has me stumped!

Hi Ben,

It's quite likely the issue comes from the customer's firewall/router. It sounds like UDP streams or NAT port mapping gets briefly interrupted or changed when a call ends. If you have a way you can connect the SIP trunk through a different firewall (I would recommend Ubiquiti ER-X with SIP ALG disabled) that would be the quickest way to test.

Much thanks! I'll see if I can dig up another router for testing purposes... I think all I have is the little Cisco RV320.