Hi Leonard! :-)

 LE>> Alas, one reason for the different networks is the fact to to
 LE>> support the density of phones found in major cities without
 LE>> needeing a cell site every block, you need to use different
 LE>> frequency bands and different protocols.
Or, as in GSM, the network can be designed to allow sharing.

 JB>> how does multiple incompatible networks lead to fewer cell sites?
 LE> Fewer sites *per network*.
In GSM networks, there are always two cells using different frequencies
between two that use the same. This is by design. GSM operates on two
distinct frequency bands, each subdivided to allow two different providers.
That means four providers can use a single cell site, and this often
happens in Germany.

Ciao
Pascal

--- Msged/LNX 6.1.1