We have several 7100's out there on v5.01 with SIP trunks. What I'm finding is that if the internet connection to the customer is dropped for a period of time, even when the outside internet is restored - the SIP trunk will not re-register. The customer will call me and I'll log into the system at 5.2.13 and change from Enable to Disable, then save. Wait a few seconds and change from Disable to Enable.

The trunk will register within about 20 seconds and will be fine again - until internet drops and comes back up and the same issue presents again.

Thanks

What do the logs show as the reason for the failure?

I had this issue with 4.8x and 4.9x.

Do you have dns servers programmed into 5.6.1?

What is the setting in 2.1.x about dns set to (can't remember where the setting is) ? .the setting is called something like multi dns?
This makes it use the dns servers in 5.2.13 and 5.6.1 and controls which order they are used in.

I think I've had this issue on and off for years unfortunately. 5.6.1 have no entries. 2.1.5 Multi-DNS is disabled.

The only DNS I'm using is in the SIP trunk settings itself 5.2.13 and have DNS1 as 8.8.8.8 and DNS2 as 8.8.4.4.

Thanks

Try putting the ip address of the server in the registration server, leave the dns for the proxy server

Sorry - not clear on what your saying. Could you elaborate?

Send me a photo of the sip trunk settings page and I'll explain better
Or send me a download and I'll make the changes and send it back to you

5.6.1 have no entries. 2.1.5 Multi-DNS is disabled.

Enter both DNS 1 and 2 Enable Multi-DNS

See if hte system re-establishes SIP Trunks after reboot.