How to Link a Phone to a Yahoo Accountby Daniel Hatter
During the initial Yahoo account setup you are given the option to link a mobile phone number. If you didn't take advantage of the opportunity at that time, you can link it to your account in your account settings. Then if you ever forget your password, you are given the option to have a reset password sent to your mobile phone via text message.
Sign in to your Yahoo account and visit your Account Information page (see link in Resources).
Click the "Sign-In and Security" menu and click the "Update Password-Reset Information" option.
Scroll down the page to the "Mobile Numbers" section and click the "Add Another" button.
Type in your mobile phone number and click the "Save" button. Click "Done" to return to the Yahoo page you were on previously.