If you're one of the lucky few to have a broadband connection in an area where there's waiting lists, will initiating a change of isp's force you to lose your connection all together and throw you to back onto the waiting list?

The reason I ask, a friend of mine had Vodafone knocking on their door offering them a deal if they changed from Telecom, and there are definitely waiting lists in their area for broadband, heard this from people up the road.