Pairaphrase can use your cell phone to validate your identity when logging into your Pairaphrase account. Unless you are using SSO, Pairaphrase requires two types of authentication to log in - a password and a verification code.
Pairaphrase can send verification codes to your email, however, more and more companies are blocking automated emails to protect against phishing and ransomware attacks that are usually initiated by a user clicking on a link or button in a malicious email. Therefore, sending verification codes via sms to a cell phone is considered safer.
Authentication apps like Google Authenticator, Microsoft Authenticator or Twilio Authy also require your cell phone in order to operate. Pairaphrase only uses your cell phone number for identity verification. Pairaphrase never sends marketing messages via sms.