One number keeps sneaking through my reject/block call list.

[bigstormgirl]

Not sure what is going on, but one phone number (out of 6) keeps getting through my reject list and leaves a vm message. I got Mr. Number app to see if it would be able to block it (suppose to hang up on caller and not be able to leave vm), but it did the same thing. Why is this happening with just this one number? Is the caller gettting around a reject list and Mr. Number somehow? TIA