This is a collection agency called "Allied", which I have heard of before--so it is a legitimate company. However, they do use extremely old data. I had a roommate from over 14 years ago and they some how linked my new home phone that I have had for abot 10 years with his name. They will call anyone who lived with the person they are trying to find.
If this is a debt collector, they are not legit. My credit is perfect. Also I've had the same phone number for nearly 28 years, so there's no way they're trying to collect a debt that old from whoever had the number before.