Kyle,
You say "one-way audio" but then say you are unable to hear "any conversation". Just to clarify, do you have one-way audio when the call is connected? If yes, which "way" is the audio reaching the other end? Dial tone is not an indication of a successful media stream to your IPC (just as an FYI).
In addition to the above questions, can you describe audio experience when you call another IP phone? Another soft phone? Also, when you place this call are you going through a VPN? Software-based? Hardware-based (on the remote site)? Is there a difference in behavior if you call when not going through the VPN (if that is possible)?
Thanks,
Bill