Did a little research, and it sounds like its a scam or telemarketing service using caller ID spoofing. Apparently the caller ID system is pretty easy to spoof (there's just so much faith in it that nobody has developed security measures for it). You probably either ended up randomly on a number list, and they have an automated system that goes down the list calling all the numbers similar to yours, or somebody got your number online, added it to their database, and is using a number close to yours in hopes that it will catch your attention and you'll answer. Doesn't look like there's much to do except block it, ignore it and hope they stop, or change your number.
This shit is really irritating. I've been ignoring a pharmaceutical telemarketer service for about 6 months now. They call every other day from a different number despite having demanded to be removed from their lists. Anybody have success getting rid of guys like this?