business phone advice

Hi.  I'm looking for some solutions.  I have a small service company in rural Texas.  We're spread out over a large area and frankly the ATT regular coverage here is spotty.  Customers generally have to call 2-3x to get connected.   There are three drivers, each with his own personal phone number. I do, too. The business has a dedicated iPhone and phone number too.  I'm often out of cell coverage, so I am thinking of getting a satellite phone.  But, the sat phone is very expensive - you have to pay a ton for outgoing phone calls.  It's a Catch-22.  Nobody knows I'm out of range so wouldn't know to call the sat phone number.  Here's what I need advice on-how to set up a system to transfer calls to the correct person (press 1 to reach driver in city A, press 2 to reach the yard, etc) from the main business phone number.  And, any suggestions on how to incorporate that sat phone would be great too.  TIA  Robert