Trusted phone number no longer in service

Enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification email option. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage

Apple ID – Forgot Password  *      

If you have 2 Factor Authentication enabled, if you can't recover the password using the steps above, you will need to use Account Recovery, using the steps posted above.

1. login on the web on your Apple ID
2. On the verify screen, click cannot access trusted devices'
3. Enter your recovery key in the pop up window
4. Go to security and change your trusted phone number

If you're not in possession of your recovery key, see this Link on how to enroll in account recovery

How to use account recovery when you can’t reset your Apple ID password - Apple Support