If you mean the messages came from a restricted number, then really all that means is that whoever sent them had their number restricted. Alternatively, although probably less likely, it's possible they were sent without even a phone, but through some application, like an IM application, or something like that, which might show up that way as well.
I hate those. Every now and again I get several calls, usually in a row, from some idiot with a restricted number who won't leave a voicemail and hangs up when I answer. I guess he realized it was a wrong number when I answer, but he's not smart enough to understand he's got the wrong number when my voicemail picks up, so he redials the number wrong number. Stop calling MORON!
It's times like this when I wish someone would invent a taser that could be sent via phone lines to the recipient of my wrath.
No, my refrigerator is not running and I don't have Prince Albert in a can. Now get off my lawn.