Originally Posted by skeeter7
I go to the main page and hit "Mail" on the right. Sign in as usual then the page asking for the phone number comes up. On that page, there is a box to enter the phone number. Just below that to the right, I have a big yellow box that says "Save & Continue". I just click that without entering a phone number and it proceeds to my mail page.
They've been asking me for the same thing, and clicking the "save and continue" button puts me into my main account. If that doesn't work for you to bypass the requirement, you'll either have to enter the number (not recommended) or have to call Yahoo customer service directly.