Buying a second hand Mobile phones is not so bad and not all that risky as most people view it, only that you need to know what to test for and you are good to go.

Before buyiny you may need to test for the following
1. microphone, make and receive call
2. the speaker, play sound and video. If formatted, insert your memory card
3. go with an ear piece to test audio port
4. test the charging port very important, (Remember the phone would not come with charger)
5. insert you sim and memory card, test for networt signal and signal strenght.
6. Auto configure your internet and try to browse (Pay as you go may be faster) or go with a sim with activated data plan
7. Test the cameras, front and back.
8. Test camera clearity and flash light.
9. Test for high temperature, most malfunctioning phones becomes unnecessarily hot when you make a call of one to two minutes or play low end game.
10. Test all keys, volume keys,power key, key pads if not touch screen. Ensure there is no hanging or delay in response when pressed.

You will notice that i didn't include battery, most second hand phone battery are not all that good and a bad battery doesn't mean the phone function is bad, its' a two different thing. You can get a new battery just ensure you factor it in your price bargain.

NOTE: When you are satisfy with all these condition and you are willing to buy, ensure the phone doesn't leave your sight some sellers could be dubious.

Additional info are welcome

play a 4 minute song and a movie for at least 15 minutes from ur SD card.

11) KNOW THE HOUSE, FAMILY, FRIENDS,FRIENDS OF FAMILY, NEIGHBORS, CHURCH/MOSQUE OF THE PERSON YOU ARE BUYING THE "second hand"PHONE FROM......
TALKING FROM EXPERIENCE

F.K.O:
11) KNOW THE HOUSE, FAMILY, FRIENDS,FRIENDS OF FAMILY, NEIGHBORS, CHURCH/MOSQUE OF THE PERSON YOU ARE BUYING THE "second hand"PHONE FROM......
TALKING FROM EXPERIENCE

This would be hard you know