Firefox Relay is a service from Mozilla that aims to provide virtual email addresses to hide your real email address, and is now extending the service to providing virtual phone numbers.
In a blog post, Tony Amaral-Cinotto, product manager at Mozilla, explained that if you suspect that the company will spam you with your phone number in the future, or you think they may share the phone number with others, the relay service will generate a phone number for you to send to the company.
The purpose of this is to provide this alternative phone number to make it easier for you to block spam calls or text messages in the future. You can block all calls or text messages sent to your transit number, or just block specific contacts. Importantly, it allows you to keep your real phone number private, and if this is a number you use to receive sensitive information (such as a two-step verification code) through text messages, you may want to consider this.
Once you register, Firefox's phone number blocking service provides 50 minutes of incoming calls and 75 text messages per month. Mozilla's blog post states that you can use its service to reply to text messages from the previous sender, but you can't make calls or send text messages. Unlike Firefox Relay's existing email relay feature, the Phone Number Service only gives you access to a relay phone number and states that once this number is selected, it cannot be changed.
Phone Number Mask Service is also more expensive, at $4.99 per month ($3.99 per month when paying annually), while the email service offers free and advanced user options for $1.99 per month ($0.99 per month when paying annually). Finally, the new phone number feature is currently only available to users in the United States and Canada.
