When you allow your users to manage their own contact addresses you will often find your users using different number formats like xxx-xxx-xxx or xxx xxx xxx with and without the national code. And this are just a few things you might encounter.
The solution to this problem are the Called Number Format Rules available in every VoIP connection. They allow you to format the numbers the users provide in their profiles into a gateway digestible format.
Example:
Name: “International calls”, Regular Expression: ^\+32, Replacement: 0032