Total posts : 45366
Marshall gives good advice. I would add that many moons ago I engineered and managed a 24/7 life support computer system where I needed to move analog data over phone lines. I leased what were known as 3004 direct metallic conductor lines which were really intended for alarm circuits with COAM terminal equipment (phone co. jargon for customer owned and maintained…my jargon “It’s not our problem if it doesn’t work”). There are restrictions governing their use including bandwidth limits and you can get disconnected if you put audio frequencies through these lines. It was difficult to get the phone company techs to cooperate when the lines went down even though they were “red capped” meaning critical circuits.
Avoid this if you can. I worked at a carrier current station on a major college campus. We had leased broadcast quality phone lines to our transmitter sites which cost $100 / month in 1960’s. They were terrible! Very poor bandwidth, long outages without response, and the volume levels would change from hour to hour.
Marshall’s suggestion about microwave links is worth a close look. The high initial costs may well be offset over the time that you use them compared to leased lines. Plus, you are in complete control of the situation. Try calling for phone co. service at 3 AM as I have and you will learn the lesson.