I have received multiple calls with no voicemails as well. Finally answered and got the same story as you all. They kept asking me for personal information and I didn't give it to them. The whole thing sounds fishy, and I'm fairly certain they are attempting to commit fraud. Please don't give these people any information about yourselves!
That's GE Money Bank. They bought the old Mervyn's accounts when Mervyn's went under. They're trying to collect on old, expired accounts. They call at all hours on every day of the week. Apparently, the rules don't apply to them.