can someone pick up a cell phone call on a police scanner?

Yes they can! Scanner manufacturers purposely block out parts of the 800mhz band and part of the 900mhz bands that contain cell phone frequencies! But if you know what you are doing you can restore cellular frequencies!

No - or not in the sense of hearing conversations.

Since the mid 1990s, cellular phones use an encrypted and compressed digital multiplex system.

The only thing anyone may hear is a "buzz", a mix of data bursts from the cell tower and any phones on that frequency.

The very first "1G" analog mobile phones could be picked up on scanners, as they just used two separate frequencies for normal uncompressed audio either way - but that changed 25 years or so ago, with 2G / GSM cellular phones.

Those and all later ones use the digital multiplex system.

(Hold a mobile phone that's in a call, near an audio amp or active speakers on a PC and if the radio suppression on the amp/speakers is not very good you may hear a "buzz", that is the rapid steam of data transmissions being picked up; that's similar to what a scanner would hear, just a lot more from other phones a lot farther away).

no,they can not pu a phone convo on a scanner

Cell phone signals are digital and encrypted now. The days of analog cell phones is long gone.

It would not do much good- the signals now are digital and I believe encoded (after a fashion). It can be done, there is a lot of information on how too.

Now one of the interesting things is this- the police do have the technology and it has been ruled they do not need to get permission to tap into the conversation like they do for a land line.

Yes. Some scanners are able to pick up the lowest FM cell phone frequencies.