What to do when your trusted number is no longer available

Sign in to your Apple ID account page and edit / update your Apple ID details -> https://appleid.apple.com

• (Sidebar) Click Personal Information -> Reachable at -> then edit / update your 'new' trusted phone number.

All of your current options to regain access to your AppleID are outlined here:

Get a verification code and sign in with two-factor authentication - Apple Support

For future reference, it’s most strongly recommended to setup multiple voice and/or SMS Trusted Numbers AND to practice using them.

They are specifically intended for this situation and are described in detail here:

Two-factor authentication for Apple ID - Apple Support

Also a “Trusted Device” with a removable nanoSIM (e.g, your iPhone) should NEVER be a Trusted Number. (it already receives - or can generate - the Verification Code WITHOUT SMS)

Additionally, you might consider establishing a recovery contact:

Set up an account recovery contact - Apple Support

What if you can't sign in to your apple ID because the two factor Auth numbers not available. I can't change my 2fa number of I can't sign in because 2fa is sending a verification to the number I don't have.