Registration issue with Polycom phones

I have approx 20 Polycom IP550 phones running firmware
The phones all register to a local server AND to a remote server.
The settings are in the sip_main.cfg file.

In the remote site, only half of the phones register, the other half are not registered.
When I look at the logs, I see no attempts to register to the remote site.
I see that it fetches the config files via tftp.

My DNS settings are fine in my router, but I put the remote IP in the config files anyways so it should be an issue.

What could cause these phones not to register properly? They are using the same config files as the other phones. All other config files are identical, to the exception of peer username.

Why such an old version of the Firmware? Newer firmware available here:

No guarantee it’s the firmware, but it is always where I start - hate to “fix” a problem that was fixed by someone a long time ago - If you are using Endpoint Manager, you can get the updated firmware through there.

We have over 300 telephones running with that version, 95% are working fine, I don’t see why an upgrade would fix anything if all the rest are running fine.

It’s up to you - we have been doing Polycom phones since 2004 - firmware upgrades have fixed MANY strange problems over the years but you don’t have to start there - I have just found that If I did everything right and it still is not working, I start looking there.

Suit yourself.