iPod 4G and iPhone 4S Facetime call not going through?

Hey guys! I'm wondering why my Facetime call won't go through. I've been trying just about everything, and it still won't go through.

At first, we couldn't get it to verify. But after getting passed the process, we both were signed in, added eachother as contacts, but when proceeding to make a Facetime call, it would show us on the camera, and the call would go forever saying "connecting".

I'm trying to call my aunt using my iPod Touch 4G and she has a iPhone 4S. She has a sim card and mobile number in. I've tried calling her using both the email and phone number, tried shutting Facetime on and off, as she did too, but still no luck.

Help would be appreciated, thanks!