Question: how to sign up for social security?
Answer: Online; or.
By calling our national toll-free service at 1-800-772-1213 (TTY 1-800-325-0778) or visiting your local Social Security office. ... 
If you do not live in the U.S. or one of its territories, you can also contact your nearest U.S. Social Security office, U.S. Embassy or consulate.