In brief: A lot of people give out their phone numbers via online forms without considering what companies will do with them, only regretting their decision after being bombarded by spam texts, salespeople, and robocallers. But a new service from Firefox helps you avoid these annoyances while protecting your privacy by generating a virtual phone number alias.

The service builds on the browser's existing Firefox Relay product, which stops users' inboxes from being overwhelmed with unwanted messages by giving them virtual email addresses. Mozilla product manager Tony Amaral-Cinotto writes that it has blocked more than 1.3 million unwanted emails since launching in 2020.

The new Firefox Relay phone masking feature is primarily designed for those times when you're signing up for loyalty programs, booking a restaurant reservation, or making purchases that require your phone number with companies you suspect may use it for marketing or sell it to other entities for the same purpose.

The feature offers up some numbers similar to your own that mask the actual number. Calls and texts to the new number will be forwarded to your phone, but you can block everything the mask receives or just specific contacts. You can also reply directly to the last text sender, which can be helpful for verification purposes.

The most important element of the feature is that you never have to give out your real number and risk being hit with spam or having it stolen in one of the many big hacks that occur these days. And there's no need to download an app for your phone, either.

Unlike Firefox's email masking, the phone number feature doesn't have a free tier. It costs $4.99 per month or $3.99 if you pay annually, though you also get the email Relay product included in the price. There are some limitations: users get 50 minutes of incoming calls and 75 text messages a month and can't place outgoing calls or send texts to anyone specific (only the last sender), but those features could be offered in the future. It's only available in the US and Canada, too.

Check out all the details on the phone and email masking features on the Firefox Relay website.