Said he was working for lawyers. Not a lot of info. Said someone used my name to take out a payday loan.

Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt.  It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes.  The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days of receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.
Read up on your rights here, get template letters to send and also make a complaint at this government site:  http://www.consumerfinance.gov/

Also file a complaint with your State Attorney General's office.
List of State AG’s offices:  http://consumerfraudreporting.org/stateattorneygenerallist.php

Got a call from them saying they were going to send me to jail

They called me just now and said if I dont call them back by Monday back by Monday back by Monday they are going to send someone out to serve me. They also gave me a case number. I think it's a [***] scam. Dam good one they are [***] with me hard.

They sad they weren't going to send someone out to serve me. I don't know I hope it's a scam its bugging me out. They are telling me I can goto jail.