No point in spending huge $$ on kit, when as rightly pointed out, you can lift the info of the network.
Next thing is...Who do you think the Telcos are recruiting as engineers to maintain the network. Westerners, or locals. Work it out.
These engineers also have access to tools used to optimise the radio network, and this includes subscriber location algorithms. Lat/Longs for the call origin. Potential there for incoming following the call home?