USA - help. need advice, supposive 'police' called

[drug-bot]

swim called an old drug dealer (whom he only bought off once and got into an arguement with at the time) he hasnt talked to in a long time, at 8:01 pm, no ansewr, just got the machine. called back at 8:02 pm, same reults. at 8:06 pm swim recieved a phone call from a 'no name' caller saying they were the police and theres been reports that this numbrer has been making prank phone calls and will be recieving a sumons in the mail. at 8:13 another no named caller called asking for mike (someone swim never heard of a mike), dont know if this had anything to do with the other stuff.

would the police call using a unlisted number?
its all a prank?
they where the police lied about thinking swim making prank phone calls to try to charge him with something else (possibly drug related)? can they?
would the 'no name' number caller asking for mike be involved with this?

just for the record swim has never 'pranked' called ANYONE.