My boyfriend is overseas and he has set up an account through yahoo for
pc-to-phone calling. When he calls a landline there is no issue,
everything is fine. However, when he calls my cell phone, I can hear
him perfectly but he can't hear me (sometimes a word or two will make
it through, but that's all). And yes, I have full reception. My
carrier is Verizon. Does anyone know
why this might be happening? Does cell phone technology not support
pc-to-phone calls?

Does it happeN ALL THE time?  Maybe your trying to call during rush
hour in the network between you both.

Or Try a neighbors cell phone witth different phone or carrier.

Maybe it is your phone or the carrier.  Experiment.

Yes, it happens all the time. He's been trying to call between 9am and
12pm. I did just give him a friend's number to call who has sprint, so
we'll see if that works. I called verizon and the lady said that she
didnt think that any cell phone provider supported this, but I think
she was confused as to what I was talking about. Also, it is strange
that the call actually goes through and that he just can't hear
me...if verizon didnt support it at all I would think the call
couldn't go through period.