By default external outbound international dialing is disabled to reduce the chance of VoIP Fraud.

If the client requests a user have the ability to make an outbound international call

Locate the User's Seat in OSSmosis 5

Click on Edit User

Click on the checkbox labeled "Enable International Dialing"

Click the orange circle in the bottom right corner and then click "Apply Edit"

In order to place the call the user must dial the following: 011+ country code + destination number