Call Quality

The call quality has been generally good. It seems like the other party hears me alright but for me their voices seem to cut out a lot. Especially when I talk while they are talking. There is also a slight echo from my voice but not as noticeable as their voices cutting out. I was wondering if I use another access number would this problem be fixed or is this something that the whole system suffers from? I am currently using the Montreal Access number.

Edit: I am using a Blackberry 8130