Debt collection

Called from this number showed on caller id as WJM Computer Solutions.  Looking up WJM Computer solutions says they are a computer and computer peripheral  installation, consulting and maintenance company. If this is legit and not a spoofed call WJM should be charged with false advertising.  But it really was a debt collector.

Debt collector. I believe for medical bills because that is the only debt I have.

Doesn't matter, but if they are spoofing a caller ID my guess is that they are a criminal enterprise.
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