The following is also in the Apple forum but as this is a question around Bluetooth i thought i would also add it here. My old man has a iPhone 5s and BT's his hearing aids to it, at times the audio is extremely poor but by switching to the phones loud speaker or back to the phone instantly rectifies the issue.

Reading up on this I found that BT 4.0 and LTE do not play nicely with each other, and that BT 4.2 is different and fixes the problems.

Looking at the specs of the iPhone 5s,6(s) and 7 models it show the first two have BT 4.0 were the 7 has 4.2, speaking with apple support they tell me that by updating the 5s and 6 models to IOS 10 will upgrade the BT to BT 4.2 thus fixing the poor audio issue experienced with the hearing aids.

My question, is this a true statement or am I been given incorrect information? as further reading, apple may be half right in that the latest update provides the BT 4.2 features but to fully take advantage of the features the hardware must also be the newer 4.2 compliment chip.

Please help as I do no not want to tell the old man to go out and spend $1200 if he doesn't have to.