When making calls you receive the message  "You are not allowed to make this call".  This typically signifys that the user has been blocked or the credit limit has been reached.

You can check this by looking up the user under the associated company, you will see a column with either Block or Unblock for that particular user. If it says Unblock, then this means the user is actually Blocked. Click on it to change to the other state.

If it is a credit limit issue, you can navigate to the company information, then click on the PBX CDRs button. Lookup the extension and click on the "Limit" link of the extension.

 

FYI:  You should not be confused with the Block Calls button on the View company information.