Originally Posted by Regar93
Weird thing is 1) I cant hear this tone on my end and 2) the keyboard isn't even activated.
(This is on my HTC One on Sprint... need to change my device to HTC One)
Welcome to the forum Regar
This is normal behavior. My ears have observed this as a caller and as a person taking a call on prior HTC phones. Has happened for me as far back as a Samsung flip phone about 8 years ago. (Sprint network as well)
When the screen is re-activated (either through proximity sensor/ambient light sensor or hardware key), with a call connected, there can be a momentary blip of RF interference across the call for some reason.
No relation to the keyboard, except that maybe the interference has a frequency that can maybe sound a little bit like a touch tone to the person on the other end of the call. This frequency could sound different for different phones, whether the noise can be heard could
also depend on the network band of both phones.
My old Samsung flip, I used to be able to send/receive texts with other people while on a call. If you sent a text whilst on a call it created an RF blip across the live line as well, and would make the person you are on the call with wonder what in the world was going on.
I suppose the One could be different, and maybe it actually does send a real tone across and it is not just RF Interference, but the only way to test the theory is to experiment.