Naven
Answers
How do you message someone without giving them your phone number?
Use a platform that identifies accounts by something other than a phone number. Naven uses an email address or a username; Discord and Slack use usernames; Signal now supports usernames so a number is not exposed.
This comes up most for people selling something, organising a group of near-strangers, dating, or working with clients — situations where you need to talk to somebody without giving them a permanent identifier tied to your SIM and, on many platforms, to your WhatsApp profile photo.
A username or an email address can be abandoned. A phone number generally cannot: it is tied to a contract, it is used as a recovery credential on other services, and it is a strong identifier for anybody trying to find out who you are.
On Naven you are reached by an address or a username somebody already has. There is no directory, so the username cannot be used to look you up in a list of anybody else.