I had to do this due to an ISP refusing to stop billing me for services I had canceled.
Mark
Well, the phone numbers they had logged for "simultaneous" connection were all my home number! The tech admitted this was impossible, obviously, and then I had to wait for someone else to issue me a refund. For some reason they could only issue a refund of $100 and I was going to have to call back to get the rest that was owed me, so they did that. Then when I called back to get the rest, the person who was "helping" me acted like I was whining because I had already got a $100 REFUND, which was evidently unprecedented for this company. I told her like three times that the size of the refund had still not amounted to the amount that had been fraudulently taken from my credit card, so the size of the refund was really something that should shame their company, not something that made me a whiner if I still wanted the rest of the money they owed me. Then I ended up having to take the rest of the money as a credit against services. I wasn't happy with that because it meant that instead of getting punished for stealing from me and me getting overcompensated as an apology, they got off scot free, and my "apology" I got was eight hours on hold, conversations with idiots that thought I could make multiple calls from the same phone line, locked into using their ISP (one which I might very well want to dump), AND I get to pay in advance! I should have filed a complaint with the DA or the state AG.
Since the number is locked to a particular vendor, that number cannot be used elsewhere which is great protection if that vendor's database is hacked.
Also, since you can set a limit and expiration date you automatically win the argument with companies that refuse to stop charging your card.
Oh, and you can manually cancel that number at any time.