i recently connected my mom's cellphone(Samsung SCH-A950 Verizon) to her ES350, they both sync'd and everything, but there seems to be a peculiar problem...

i can't hear the other person

i tested this at home with my mom standing outside, and me sitting inside the car, she said she heard me fine. when she speaks though, i can't hear anything inside the car.

the manual isn't of any help.... does anybody know how i can fix this?