3cx Not allowing External Calls to 0800 Number

[techies]

Hi All,
Strange one, of our customers cant make outgoing calls to an 0800 number.
I compared it to our system and there doesn't seem to be any differences, anyone have any ideas?
Please bare in mind I'm still kind of a newbie on this, thank you.

 

[Alphabetic]

Check the activity log in MGMT console - may require upping the logging level.

Then check your outgoing rules to make sure you have a rule which will allow calls out to 0800.

Then run a wireshark and see what's happening.