Voicemail message: "This message is intended for [name said by mechanical voice:] Hammer2Scammers. I received a fax order regarding a complaint that was filed against you. I have been retained to serve you with documents to appear at either your residence or your place of employment. If you have any questions or concerns about this complaint or wish to rectify the matter, you can hit any key on your phone to connect to our office directly, or call us at the following number: [phone number said by mechanical voice:] (203) 516-7978. When calling, please reference file number (some BS file number that doesn't sound like a civil complaint number, also said by a mechanical voice).. You have officially been notified."
Ooooh, I've "officially" been notified!! That makes it all legit and scary, oooohh!!!
Appears to be a scam. Legitimate debt collectors send letters detailing the alleged debt, and you have 30 days from the date of receipt to respond to the letter and request more information. REMEMBER THAT: Do NOT just send money to someone threatening you over the phone. By law, they have to send you a letter.
Besides, genuine process servers don't warn you before serving complaints, as that defeats the purpose. They'll come to your door unannounced and barely identify themselves.
Source: I work in the legal field.