Action Details
Requirements and how-to articles for YouTube's action:

Verifying your account lets you upload videos longer than 15 minutes long, add custom thumbnails to your videos and do live streams.

You need this to get it done:

Account Verification
Enter a phone number to be associated with your YouTube account, which will be used to send your verification code to.
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How-To Articles
A list of useful links for you:

YouTube Help - Verify Your Account By Phone
Instructions on how to verify your account.
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