Cannot call company numbers - Busy tone

[@ndr0id]

I have a user that is unable to call internal office numbers, not just the extension it's the whole ten digit number. This does not happen with other calls with the same area code, only calls within the office we work for. The user is able to receive calls from the office but when the number is called back all I get is a busy tone. I have tried to change the Smart Dialing settings with no luck.

Has anyone seen this before? I've been searching and cannot find anything that helps.

Thanks!