I need to build a (generalized) model of the economics of a cellular
call.  I understand the revenue side reasonably well (ARPU, etc.), but
am quite unclear on the cost side.  I am not referring to the CPGA so
much, but more to the cost paid between service providers for
originating/terminating calls, interconnects to long distance/local,
mobile termination rates (are there any in the U.S.?), etc.  I assume
those are the major costs included in the "cost of service" category? 
Have I missed something major?

Bonus:  While we're at it, what are the (generalized) economics of a
cellular tower in terms of costs, supported simultaneous calls,
scalability, etc.?

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