The concept of globalizing numbers and then turning right around and localizing them before presentation to the phone initially seems confusing and non-nonsensical. However, after further deliberation and understanding this concept begins to make sense.
Globalizing is the act of modifying all numbers so that they are in a common and standard format. It can be said that it is a way of taking the dial-plan scheme and normalizing the number set. This allows the format of the incoming numbers to be understood around the world (globally) since they are in a standard format. This standard format is referred to as the ITU E.164 format and is signified by number being prefixed with a “+” sign.
When you can assume that every incoming phone number will be formatted consistently, you can deterministically create translation rules to add any required routing digits such as 011 for international calls, or removing the 1 for local calls before passing the call to the PSTN, Phone or next gateway.
International E.164-number structure for geographic area
Localization is the process of then taking the incoming (normalized/globalized) number and modifying it such that the caller-id is in a format more easily understood by the end-user at that particular location. For example, a 10 digit number without the + sign prefix.
- Workshop on numbering planning and convergence of numbering, Recommendation E.164 – E.169, Martha Onyeajuwa
- Globalization Prezi, Theory and Reasons, Mark Snow