Frustrating problem...

Starting Thursday around midnight, I started to get phone calls on my cell phone from a number very close to mine.

If my number were 123-123-1234, the number calling me is 123-123-1233...the last digit is one off from mine.

I've had about 7 calls in 48 hours...not a lot, but enough to be frustrating. They come in at midnight, 2 AM and a few times throughout the day.

When I pick up the call or when I let it go to voicemail, the result is the same: a recording saying: To accept this call press 1.

I have called the number and spoke with the guy 3 times. He has no idea why his number is showing up as calling me b/c he isn't calling me. I have asked if he has Google Voice set up on his phone or any of his phones b/c that what this sounds like to me...he's clueless.

I called ATT and they can allow me to block this number...for $5.00 per month.

My phone allows me to reject the call, but that just sends it right to voicemail and I still get the notification that I have a voicemail.

I'm about to head out of the country and I don't want to spend $ getting these calls or listening to the voicemails.

Short of changing my cell phone number or paying the $5 per month, do I have any options?