How do I approve my iCloud keychain if I don't have access to my old phone number to get the code?

Hello NidaMazel,

After reviewing your post, it sounds like you want to setup iCloud keychain but dont have the phone the code was sent to. I would recommend that you read this article, it may be able to help the issue.

Frequently asked questions about iCloud Keychain - Apple Support

A verification code is sent via SMS to this phone number. If you can't access this number, contact Apple Support, who can verify your identity, so that you can complete setup on your new device.

Thanks for using Apple Support Communities.

Have a nice day,

Mario