All three phones display this behavior. It is not a volume issue - the phones ring normally when they are out on the table, desk, counter, or in a vehicle, etc. Put them in a purse or pocket and they will only vibrate, they will not ring. Take the same phone, remove it from the pocket/purse, call it again, and it rings just fine. This certainly seems like a feature I've seen described as "Pocket Mode", but we want to disable it so the phones always ring.