Transfer fron AT & T to Spectrum mobile

PH - Dec 5, 2021 at 09:02 PM
How do I transfer my contacts and messages on my iPhone SE 2020 2nd Gen and iPhone 11 currently using AT & T to my Spectrum Mobile SIM card? The link in the so called tutorial sent by Spectrum Mobile tech support just does not work. I'm not sure if I've backed up all data on my phones to iCloud