The EchoLink program allows worldwide connections to be made between stations, or from computer to station. There are over 200,000 user worldwide, with more than 5,000 online at any given time.
Provided below is a link to a video on Echolink / VoIP presented by K1RFD -Jonathan Taylor. Echolink is a freeware Voice over Internet Protocol (VoIP) program that was created by Taylor.
Echolink / VoIP Video by K1RF
Video timeline
01:58 Start
18:47 IRLP
21:00 EchoIRLP
21:39 Asterisk
24:00 Phone Apps
27:50 Networking
The link below is for a PowerPoint presentation on EchoLink.
Single most common problem with Echolink Setups are due to Firewalls.
EchoLink requires that your router or firewall allow inbound and outbound UDP to ports 5198 and 5199, and outbound TCP to port 5200. If you are using a home-network router, you will also need to configure the router to “forward” UDP ports 5198 and 5199 to the PC on which EchoLink is running.
http://www.echolink.org/firewall_solutions.htm