mysudo, it's not a recommendation, just an indication that phone numbers are moving from the base layer of the phone to a disposable app that will become as relevant as faxes are today.

As for the service, I'm pretty certain it's not open source, but it is a service that focuses on privacy and allows you to create disposable mobile numbers, or segregated mobile numbers.

If you are in the US, Google have a free option, outside of the US, we have to pay for services like this.

For me, my NIP-05 is my primary phone number from now on.