You can verify the number even if it no longer exists.
If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (get Apple’s own instructions in this article: How to use account recovery when you can’t reset your Apple Account password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity. One tip to using account recovery it to look for options in small blue letters beneath the normal log-in items if you cannot complete the requested information.
Here are links to posts by Community contributors which provide additional detail about the account recovery process and what to do if you do not receive a text or call: Activation Lockout Issues - Apple Community and How can I reset my Apple Account password? - Apple Community . This thread outlines the multi-step process and final recovery —> My Apple ID is locked, how do I fix it? - Apple Community , and this one about things you should and should not do while waiting —> How can I recover my Apple ID after multi… - Apple Community
Failing recovery of the account, as you know from How to remove Activation Lock - Apple Support:
Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Read the requirements and steps for an Activation Lock support request at: https://al-support.apple.com/#/additional-support Apple says you need to have "proof of purchase documentation” and “proof of ownership documentation”, but does not detail what currently constitutes proof other than it “must include the product serial number, IMEI or MEID.” User reports on this community indicate that typically Apple will ONLY accept an original receipt issued by Apple or an Apple Authorized Reseller. Presumably this is the only kind Apple can authenticate against fraud since Apple is not involved in third party sales. Apple recommends that you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support
Note that the device cannot have Lost Mode set on it. If your device has been taken over by you having entered a scammer’s Account then the scammer may have set that too and the device is lost to you.
If Apple resets the device this will give you access to the device but won't restore access to the account used to lock it. There is nothing that can be done to expedite an Activation Lock request.
