Even in the 6th generation of iphone is not prone from issue in very basic feature of calling. User have been following Apple ipone support for various call issues but the the issue raised is like “why does my iphone 6 keep muting unmuting itself”. The problem is even reported whith iphone 7 users that “iphone 7 mutes itself while on call” while holding the iphone 6, it automatically mutes (and user are pretty sure nothing is touching any buttons on Apple device) and sometimes iphone randomly calls someone in my phone book which is even more weird. This can be in the middle of a call using earbuds with the phone sitting on my desk and the phone mutes automatically. However there are no clear guidelines on this issue from Apple support but below few fixes may help to fix the issue.
Fix 1: Turn on data
Though weired to hear but this fix Iphone 6 is muting speakerphone automatically.
- Reset the phone (hold down home and power buttons until the apple logo appears)
- Turned off "hand off" (settings -> General -> Handoff & suggested apps)
- Turned off voice over LTE (VoLTE). This is the one I think is least likely to be causing the issue, but I tried it anyways. (settings -> cellular -> enable LTE -> Data Only)
Restart the iphone6 and check
Fix 2: Clear the ports on phone
When one of the user approached the Apple customer care after a long discussion Apple seems to reply with clearing the calling ports of the iphone, user had a tiny piece of clear film over the mic next to the headphone socket. Peeled it off & all seems to work since then.