I have an iphone 4S for one of the numbers on my account.
I have an iphone 5 that was attached to another number that is no longer being used.
I would like to swap from the iphone 4S number over to unsued the iphone 5.
I've spent over an hour drilling into the site and my account settings to try and find this function. I can only upgrade to new or modify settings on current device/line.
Where is this feature on the website?