A cell phone conversation (or any phone conversation) once it reaches the phone system, becomes a stream of bits (occupying one of 24 channels in a T1 connection, etc.). The key in the digital world is establishing the link between the two ends of the conversation.
The government has required for years that new phone technology still allow the provider to tap the phone conversation at the (legal) request of law enforcement. Usually, this is a matter of telling the switching computers to send a duplicate of the data stream to a device which will record it. Pretty simple, if the switches and routers can handle the request. Newer ones can.
Of course, Podunk T&T likely still has the old electromechanical switches, so this discussion is probably irrelevant for them.
Would someone do it as a “favour” outside of legal channels? As previous poster said, how many small-time phone compaies are left? the big ones probably are not amenable to persuasion from small-town police. Any employee doing such a favour would quickly find themselves fired. The process is likely monitored and logged to the nth degree to prevent such abuses. The upper management understands that a “friendly” employee puts the corporation at risk of millions of dollars in lawsuit dmages, and one disgruntled tech employee can blow the whistle. (As happened with Cheney’s ATT data eavesdropping). Maybe you share coffee and donuts with the local Boss Hawg, but is it worth losing a pretty cushy job over?
The motivation is even stronger. As Pelicano is finding, illegal wiretapping is illegal. It can - even if at the (illegal) request of the police - possibly result in a long stay at the crowbar Hilton. It’s not nudge-nudge wink-wink. A simple regime change or disgruntled employee or principled judge runs the risk of sending you to jail. Do some people still do stuff that can land them in jail, even as just a favour? I’m sure they do, but it is a pretty good general motivator to hew to the straight and narrow path.
The NSA of course, has nifty gadgets that can point at a microwave tower and read the conversations on the T1/T3 streams going by. Of course, as the world’s microwaves go silent the NSA has other tricks - there was an article in wired about how they stole a scientist’s patent for underwater fiber optic connectors. Wonder what those are for?
The NSA is forbidden from spying on US citizens on US soil. Despite the twisted interpretations of Cheney’s tame lawyer monkeys, that’s pretty much ruling out listening in on local conversations inside the country. Again, it IS illegal and anyone going along without direct assurance from the VP himself is probably putting job and freedom on the line, if not now then in 10 or 20 years.
So the question is, what grounds do police need for a warrant?