jdavis/twofactorauth — pull request #239 by fongandrew (2014-03-20 00:00:13+00:00)
Title: Cloudflare doesn't support SMS-based 2FA

Their current implementation of Authy may use SMS to verify a phone
number, but actually logging in requires installation of the Authy app.
A 2FA login using only SMS without the Authy app is not possible at this
time.