Not receiving any calls on my Moto G 2 (recently upgraded to Lolllipop 5.0.2) Usually I use use this phone only for surfing internet. One day I thought of calling my number from a friend's cell, it rang once and then sent a busy ringtone. I am not able to figure out what the problem is. It was working fine with Kitkat.
First go to settings > Sim cards and check the whether sim is enabled,
If disabled then enable the sim.
if the problem happens again try to reset the phone