At&t To Glo Ng How Does That Work. Help Please

Hey!
Well I would appreciate any help I can get on this.

I recently arrived in Nigeria and my At&t network switched to Ng Glo on its own. I've spent some time on the Internet trying to figure out the billing and all, still cant find the info i need. But when people call my att number I still get my calls from the US.
  Anyone got some info. Thanks in advance

The Service is called Roaming. the ability to use yur phone in a country where yur host network

has some agreements with the country you are going to. In yur case, Glo is yur roaming partner

beta be careful, the roaming charges might cost yu an arm and a leg,  well at least in my case.