Signal is rolling out usernames to everyone, eliminating the need for phone number sharing
Signal, the encrypted messaging service, has officially launched its username feature to everyone following a beta release two weeks ago. This allows users to connect with others without the need to share their phone numbers. To access this feature, users must update to Signal version 7.0.
With the introduction of usernames, phone numbers will no longer be automatically visible to chat partners. However, those who have a user's number saved in their contacts will still see it.
Users who prefer not to share their phone numbers can now create a unique username for use on Signal. However, a phone number is still required for the initial sign up.
A new optional privacy setting has also been introduced. When enabled, users can only be found by their exact username, making it impossible for others to initiate a conversation or even determine the existence of a Signal account using a phone number.
To leverage these features, both parties in a chat must be using the most recent version of Signal (7.0+).

Comments
I'll gladly switch to Signal when they give me control over my own data and let me sync chat history to new devices.
Signal makes the most sense as an alternative to WhatsApp, especially now that phone numbers can be hidden to other users
I agree. The greatest difficulty is convincing other people to use Signal instead of Whatsapp.
I started using whatsapp with my family. This is over.