Mobile Phone Hanging

Simple. Take the phone back to the supplier and demand a warranty replacement.

Do you wear your tin foil hat while using the phone?????

If yes; that's the problem.

If no; follow advice previously given by PWSlack. Tell them your phone is dropping calls.

Perhaps a reset might fix it. Make sure you connect your phone to your computer and backup anything you can like contacts, pictures, videos, music, etc. A reset will probably delete all these, but may fix the problem. I quick search for "Samsung Advance factory reset" yielded this result:

http://www.telusmobility.com/en/AB/Samsung-A885-Advance/how-to-000489.shtml

CAUTION: Resetting your smartphone deletes your ringtones, contacts, pictures, messages, and other downloaded content. If you want to save this content, use third-party software.

1. Tap Menu.
2. Tap Settings.
3. Select Phone.
4. Select Reset Phone.
5. Tap Yes.
6. Enter the password. This is typically the last 4 digits of your phone number (unless you've changed it).
7. Tap OK.

Your phone is reset to the original factory settings.