GE CORDLESS MODEL 21028GE3-A?

My 2 hand set cordless just stopped working, It rings & I can see the calls coming in,but if I pick up the phone I do not hear the other person,but the other person hears me. I also cannot call out, and my answering maching does not pick up any messages. Do I need to change both batteries in the handsets or is the base of the phone not working.

Thanks