No, that's the opposite of what they should be doing...

From The Evening Standard:

BT is facing demands from councils and police to disable the free calls function on its new “smart” telephone boxes amid claims they facilitate drug dealing and anti-social behaviour...

One drug gang is thought to have made £1.28 million worth of sales from a panel in Whitechapel. After the call facility was switched off, there was a “significant decrease in anti-social behaviour” in the streets around the phones, a council spokesman said.

Assuming that catching drug suppliers and their customers is a worthy aim (it isn't, but the law is the law), that's the opposite of what the authorities should be doing. This is an ideal opportunity for a bit of easy data mining and a fishing expedition!

Firstly, don't flag up that you know something which the other side doesn't appear to know that you know.

Sift out which 'phone numbers are rung most often and which of those result in clandestine handover meetings.

Maybe some customers are so dumb as to withdraw cash from nearby cash machines. So you know exactly who they are, with corroborative photos from the banks' CCTV, or maybe clear up a debit card theft.

Follow callers on CCTV or for real - nowadays, it is perfectly normal to see people standing or walking around wearing an ear-piece, staring at and talking to a mobile 'phone. They can use that to see CCTV footage while keeping in contact with base - now you know where they live and/or where they meet.

Clearly, you don't want to nick customers or suppliers a few minutes after they've put in their order from the public 'phone, that would give the game away, so spend a few weeks or months getting plenty of CCTV footage and incriminating photos, compiling your list of 'phone numbers, names, addresses, when the deliveries seem to come in etc.

Finally, you do a dawn raid in random nearby areas at random intervals and present the Court with some nice fat folders full of evidence.

(If you just turn off the 'phones, suppliers and customers will find some other way of getting touch, making the police's job all the trickier.)

Job done.

Until the next generation of drug suppliers steps up to the plate, rinse and repeat until they legalise,  regulate and tax the supply of the stuff.