A couple of my users are having similar problems. When they are on a call with someone internally (within the WAN) they can hear the other party but the other party can't hear them. Would someone be able to point me in a troublshooting direction to resolve this problem...thanks,
We're using CCM 3.3 but plan on upgrading to 7.X in a couple of months.
One-way audio is normally caused by routing problems. Sometimes you may have asymmetric routing and packets can make it one way but not the other. It's kind of like not being able to ping because only one side has the route :)
Make sure it's not going through a firewall, firewalls love to cause one-way audio.
You can check the webpages of the IP phone during the call, and go to the stream statistics. This will tell you the IP address that the phone is sending its RTP to. Make sure that the default gateway of the phone can ping that address and check for any obstacles along the way.