Our Iphone 5's are brand new. It's disconcerting that OFTEN the phone does not ring and goes straight to voice mail. Happened often enough to become a serious problem. Do not disturb is turned off and the phone is not silenced nor is it in Airplane mode. I have tried resetting to no avail.
Is there a fix for this. It happens to both of our phones and never happened with the Iphone 4s's
How good is the signal strength where this is happening? If you have a good signal strength and have gone through the user troubleshooting, the last thing I would try would be to remove the SIM card, wipe with a clean, dry cloth and then reinsert them. If this doesn't help, then contact the carrier as this could be something with your account. It is very unusual for two devices to display the same behavior together like that.