AGPS - Assisted GPS
Ok.. I always mistaken that A-GPS (Assisted Global Positioning System) is based on triangulation of mobile GSM cell tower. Now then I realized that I am wrong.
AGPS is not so fanciful at all.
Usually, network operator deploy a assisted server that download orbital information of GPS satellites periodically. Then, AGPS makes use of mobile phone data connection to connect to assisted server to obtain pre-downloaded GPS information.