An example of this type of system is the Air Force TV network used to teach civil service contracting classes from Wright-Patterson Air Force Base in Ohio to Air Force bases around the world. High-end digital phone line video teleconference systems use digital phone lines to connect two or more sites together. They range from systems that use as few as three ISDN phone lines to as much as a full T1 line. These are true two-way video systems sharing both video and audio in both directions. Procurement costs for a high-end digital system for each side can vary widely depending on the sophistication of the system.
Hourly operation can also be expensive.
Toward the top end, a T1 line system can run thousands of dollars an hour if bridged to multiple sites. Examples of high-end digital systems are many. The system connects a classroom at ERAU s Daytona Beach, Florida campus with their Prescott, Arizona campus. Some classes originate in Arizona while others originate in Florida. The system provides high quality video and good audio between the two sites.