Ask HN: Transfer analog data via digital line?

Quick Summary: The sending device is talking to the receiving device but the receiving device can not talk directly to the sending device.<p>I have a Magicjack Plus and need to send analog data to a third party. It is setup directly through the router/gateway. I opened the UDP ports 5060 and 5070 on the router and forwarded those ports to the MJ IP. It still is not allowing analog data to go through. It is talking with the other network but the other network is not able to talk back to the sending device. Any Ideal? FYI, what is being transmitted is EKG via Medtronic Carelink modem. EDIT ADD on: They talk fine with each other until sending device is done. Receiving device cannot initiate the closing statements to the sending device.