alt Hacker NewsHow do you tell that to them in the first place? You got someone's phone number. The person who gives it to you tells them that they use whatsapp. You can't even tell them "Sorry I only use Signal" unless you open whatsapp app.
Replies
kelnos • last Wednesday at 9:56 PM
Presumably at the time they've given you their phone number, they've told you that they are on WhatsApp, and then you've responded directly that you're only on Signal.
If there is a communications channel by which they can give you their phone number, you can use that same channel to discuss what messenger to use.
prmoustache • last Wednesday at 6:58 PM
If they can't reach you via whatsapp, they will call you.
You realise you could use that phone number to...call them and let them know? Also - in what situation are they giving you a phone number and telling you they use WhatsApp but you having no way to respond when receiving that info? If it's in person you can explain at the time. If it's taken from a website, call them. Or you can even fall back on SMS.