does not leave a message

No, this is likely a scam. Wait for the process server, I bet he won't show up. Real process servers don't call to warn you (you may leave town), they just show up from nowhere and serve you.

Legit collectors per section 809 of the FDCPA http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre27.pdf *must* tell you at initial contact, or send you paperwork within 5 days of initial contact, the following:
1. $amount of debt,
2. name of the current creditor (which may differ from the original creditor who might have sold your debt),
3. a statement that that debt will be assumed to be valid unless you dispute in writing within 30 days,
4. a statement that that if you do dispute in writing within 30 days, the collector must mail you written verification of the debt,
5. a statement that if you ask the collector in writing within 30 days, the collector must send you the name and address of the original creditor if it's different from the current creditor.
If you don't get the 5 disclosures, orally or in writing (you do not have to ask for them, the FDCPA requires collectors to provide them), treat the collector like you would any SCAMMER. Scammers are using bought/hacked loan application data to extort payments for fictitious debts from victims and victims' families and friends.
The FBI warns about payday loan extortion scams here http://www.fbi.gov/news/pressrel/press-releases/paydayloanscam_120710
The BBB has issued several alerts on this scam, just google "bbb.org alert phony debt collector"
Report to the Internet Crime Complaint Center http://www.ic3.gov/complaint/default.aspx , the Federal Communications Commission http://esupport.fcc.gov/complaints.htm , the Federal Trade Commission https://www.ftccomplaintassistant.gov/ and your state AG, as appropriate.

I received a message from this number, but the man said he was Jack Rooney and did not say what law firm he represented or what or who was suing me.  Just that I should expect to be served this afternoon or Tuesday.  Should I try to contact and see what he is about?

The do***e bag above listed as "Smarter" must work for these scam bags.  They are all Scams!

So what were you served?

Just updating everyone from my previous post. I did not receive paperwork on Friday, January 7th but first thing Saturday morning i did receive it. On a side not the server Mr.Hill looks like Grizzly Adams.

I received a call from a Thomas K. Hill on Wednesday, January 5, 2011.  He told me that he needed to verify my information so that he can serve me some papers on Friday, January 7th.  I have received calls on my work and cell phone.  But the number he left for me to call back was for the Law Office of Anthony H. Rodrigues.  I looked this company up because they were not listed in the BBB registry.  They have numerous complaints against them.  I think this is also a scam company.  I guess I will find out today if they are or not.