system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When I'm on a cell phone, and I can hear the other person crystal clear, but they say the quality is so bad on their end that they can hardly understand me, what's going on?
gpt
Cell towers have more power than a phone, so "tower to phone" is more reliable than "phone to tower".  For example, if you are close to your tower and the other person is far away from their tower, they can hear you fine, but their return signal may have trouble reaching the tower.