I have spoken to a tech support person about this problem. They tested my modem and everything is working properly. When I make an outgoing call to my sister, I do not hear any ringback. At first I thought I wasn't connected and kept hanging up. I didn't realize my sister had actually answered the phone and she could hear me talking but I couldn't hear her. The tech support person said the problem is at her end. I told her about it and she said she has no trouble with any other callers and she hasn't made any changes to her phone system that would prevent me from hearing ringback when I'm calling or from hearing her voice. Has anyone else has this problem?