Q: iCloud keychain verification

Welcome to Apple Support Communities, janellyb!

From what I'm understanding, the confirmation code to start using iCloud Keychain on your new iPhone keeps getting sent your old iPhone number. I've run into this problem myself and I'll do my best to help.

Frequently asked questions about iCloud Keychain -- Open this article and scroll down to the heading "How do I set up iCloud Keychain on a new device without another device to approve from?"

From what you're describing, you'll need to contact our Account Security team for help. Since they're only available through Phone Support, use this link to find the best number to reach them -- Contact Apple for help with Apple ID account security

Take care and thanks again.