Building to building Wireless RF just took a giant leap for mankind. Just imagine 100 mbps throughput - full duplex - up to 7 miles and toss in 2-T1's for icing on the cake. The price for this product is not for the faint of heart - call it $60,000 installed. Your T1 is costing $15 to $20 K a year (with line charges, equipment and maintenance). Your Frame Relay is costing $12 to $15 K a year (line, port, CIR, equipment and maintenance). Depending on your situation, you could be spending $30K to $50K per year on communication charges. So, a payback in 1 to 2 years could be waiting for you and it is called Stratum.
For those who are lucky enough to be able to look at hard wiring between buildings, putting a pipe in a trench through a heavy parking lot will cost $100/ft. Add the cost of fiber or copper, not to mention the disruption to business while the trench is being installed. Then of course there are the permits and the inspectors as well as the local utilities.
So if you are over 200 feet away, the RF pays for itself plus you get the bonus of being able to move the RF in the future if you change locations.
If the 100 meg (each way) plus the T1 is more than you need, how about this - 20 meg each way and 2 - T1's for $35K. And this unit can be upgraded to 100 meg if you grow into it.
This RF implementation requires a clean line of site and a bit of Path engineering. Give us your rough details and we will get the ball rolling.

Does this sound like a great solution or what?