888-518-4403

This is a debt collector calling about a "pre legal matter".  Typical debt collector.

+1 888-518-4403 not sure how they are legit. Collector when their number is not listed online they were calling and harassing our family members which makes me wonder how they got all our numbers seems like a straight scam

No - a typical debt scammer.

Also received a threatening call. He also called one of my daughters. If he calls back I will ask him for documentation. That will stop it fast.

I called back and no answer. I left a message with my lawyer's phone number. Lets see if that stops them.

This is a common ploy by criminals masquerading as debt collectors who are attempting to extort money from people by scaring you into believing that you will be criminally charged, go to jail, lose your driver’s license, have wages garnished, be sued, and a variety of other variations on this,  all for an alleged or nonexistent debt.  One of the tricks they use is to call your work place, friends, or relatives repeatedly in an attempt to shame you into paying.  They also use the “process server” ruse who calls and claims he is going to serve you, but then says you could avoid it by calling another number

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