I'm asking for my significant other who's setting up a new iPhone. She currently has her old phone with an old Apple ID and is getting a new phone with a new Apple ID. Can she still use the same phone number with the new Apple ID? What steps does she need to take for iMessages? Does she need to unregister her phone number from the old Apple ID and register it with the new one? Also, what will happen to her group chats in iMessages?
2 Answers
To keep everything organized, she should migrate her data rather than just switching accounts. On the old phone, she can go to iCloud settings and gradually disable apps using iCloud. When prompted, she'd confirm downloading the data. After that, log out of the old Apple ID and log into the new one on the old phone; this should make her data accessible on her new device.
She shouldn't really create a new Apple ID just because of this. If she's switching, using the same phone number with her new Apple ID is possible, but she needs to be careful about how she transitions.

Sounds pretty straightforward! But since she doesn't have many important apps, the main focus is really keeping the iMessages intact, right? It’s good to know the pictures and videos have already made their way to the new phone.