Strange Extension Cross over


Im getting this really strange issue where extensions are randomly calling each other.

For example:

Company A has one sip trunk pointing to a ring group including:
extension 401 belonging to company A
extension 402 belonging to company A

Company B has one sip trunk pointing straight to:
extension 210 belonging to company B

The system is using Custom Contexts to separate the companies.

The problem im having is that firstly for internal calls if extension 401 calls 210 it calls itself, if extension 402 calls 210 it calls either 210 or 401 randomly.

If 210 calls 401 then it calls itself, if extension 210 calls 402 it calls fine.

regarding external calls: if someone calls the external number for Company B then it randomly calls either 401 or 210. Im so confused!

Any help would be so good!

many thanks,

Hi Guys,

Iv managed to fix it but ill post it here for future reference

It fixed when I updated the firmware on my handsets Yealink T22p! this was a brand new handset which the firmware must of been corrupt on. Iv since found another Yealink handset doing the exact same thing and it had the same firmware version on it! updated the firmware and it fixed!