Does anyone know if there is some type of phone service provider(s) or some sort of software package that changes a person's phone number for every call? For example, I rec'd a call from 555-1212 but did not answer...less than 30sec to a minute later my phone rings again w/a different #, then again w/a different#, and all of a sudden, I would stop receiving calls all together for a while.  Does anyone know if this can be true that someone can call u with different numbers that show up for caller id purposes???