Banking's Physical Security

We all know that banks are very highly protected as far as their money goes but how safe are there computers? I live very close to a computer database collecting company that collects the data related to many banks in the area. It is all done through land lines and is not very well protected. They aren't very careful about who or what they let into the building also. If someone were to cut the lines the banks in the area would be out for days and they wouldn't have a means to do interbank transactions outside of the immediate area. Has anyone else seen this in there area or heard of it. Wouldn't it be a better idea to do the transactions by satellite.