Challenge: Sourcing Location Based Mobile Phone Numbers

I wrote earlier about our last board meeting where i developed a serious headache, price fixing... Blah blah. Well, that meeting was about a new service we were introducing, which is Location Based (Customized) Bulk SMS Advertising.
Of course customized bulk SMS sending ain't a new thing, we've been offering customized SMS services for a while, but customers come with their own target phone numbers.
This time around, there's a clause being attached: location to the bare bone, i.e local government/town specific. The idea came from a job we're about to get. A local government chairman gunning for senate asks us if we can aid his campaign with text messages to people within his senatorial district, and we have to start sourcing numbers within his district. Think this explains the extremities of our last meeting, the price fixing etc. Turns out number sourcing ain't all too easy.
I'll keep posting as things turn out.