IRLP

The Alabama Link is available on IRLP at experimental reflector 0090 (Click for Dashboard)

IRLP stands for Internet Radio Linking Project here is an excerpt from their web page:

The system starts by receiving audio into a radio that has been modified to interface with a computer (using the IRLP interface board). When a signal is received by the radio, the COS state changes. This change is then sent to the interface board, which tells the computer that the COS line is active. This change is picked up by the IRLP software and the computer starts sending a packet stream containing the audio from the receiver.

This audio is picked up by the connected computer(s) and played out the sound card. The IRLP software detects the incoming packets and sends a PTT signal to the link radio. Hence the audio from one end is heard on the other.

An embedded node (Courtesy IRLP.net)
A raspberry pi based node (Courtesy IRLP.net)