AT&T cross upgrade question

That is something I would do at the store. What usually happens is they will upgrade the line B and then switch line B back to the original phone.

I have never done that over the phone before but I do it at the store all the line with no issues. Ask them though, they maybe able to handle it well.

 

I've done it over the phone. The thing to be mindful is do not turn on the phone when you receive it. Call the att line and there is an option to activate a phone on a different line than what it was ordered under. You will speak with a rep and you will need to provide the IMEI and CCID (sp) number. Once thats done on the system you will then proceed with turning on the phone and activating as normal.

 

I've done this twice now. The first time they said the sim MUST be burned.
The second time they let me keep the sim active (my husband was at work when I bought the 5 and activated it on my line, leaving him on his 4). I just asked them if I could please keep the same sim.