Customer lock-in in only four easy steps! 1. Sarah gives out her new number to people she meets 2. They add Star Star SARAH to their address books 3. Two yea

Customer lock-in in only four easy steps! 1. Sarah gives out her new number to people she meets 2. They add Star Star SARAH to their address books 3. Two years from now Sarah wants to switch to Verizon 4. But uh-oh! Because this is an add-on it probably isn't subject to the same portability requirements as regular numbers, so now she is stuck with Sprint.