I have done work at a utility company who is using microwave in a similar fashion.  They have a definity in the middle with analog ports pointed at their remote sites via their own microwave towers and network.  At the other end they are putting the analog ports into partner systems as pots lines.  Go off hook on the partner and you have dial tone on the main switch.  Pretty neat.

how the signal is converted at each end is beyond what I have been involved in - but I assume it is a "wireles T1" into a channel bank of sorts.

Adtran has some great stuff.  Try www.adtran.com.  They have an off the shelf wireless microwave dual-t1 unit, an endless array of integrated access devices IAD to mux out DS3/DS1/D0's, and the smaller TSU600's act as T-1 to 24 port FXS muxes.

What you have described exactly matches their dual T-1 microwave unit (I forget what they call the model) combined with TSU600's on each end.  You can get the 600's on ebay all of the time and I've seen the microwave stuff on occasion as well.

THIS STUFF HAS A 5 YEAR TRANSFERRABLE WARRENTY!!!!!!!!!.  It's indestructable.  No I don't work for or sell Adtran, but I use it daily and love it!

-CL

the adtran product is called the Tracer.  There is also a product by Western Multiplex (wmux.com) that is quite affordable.

jim
www.tgscorp.com

The Western Multiplex product also works well
http://www.proxim.com/products/all/lynx/LynxHD.pdf