I was wondering what a phone call would be like entering or falling t=into a black hole. Due to the massive density of the black hole and time would feel slower, how would that appear to the person on the other side of the call?
You and your phone will be destroyed before you get to the black hole, but If we pretend that you and your phone can survive being in the vicinity of a black hole ... And let's suppose this is a regular black hole of about 5 to 10 solar masses, and you are falling in, you are not trying to orbit it.
As you fall towards the black hole, at first there is no problem. As you get closer to the event horizon you will accelerate, but until the last second or so the relativistic effects are quite small. Your phone signal will be redshifted, so the receiver will have to adjust the frequency that they are listening in on.
The last second before you fall in will last forever. Your signal will become redshifted further and further, your apparent rate of speaking will slow down and the last second before you pass the Event horizon will, to the outside observer, last forever.
You however are doomed. You pass the Event horizon and reach the singularity in a fraction of a second.