How to implement sending a message from the site to the messenger?

Question

whatsapp

Good afternoon, wt. experts, tell me how to implement the following thing. Cool if you give a link where to read in detail.
You need to do the following:
There is a website, you need to confirm the phone number via:
SMS;
viber;
whatsapp;
Telegram;
SMS - I can do it myself. But I don’t know what to do with messengers.

If anyone has information on this, please let me know.

Answer 1

By phone number you can only Viber and WhatsApp, not very cheap and only for business.
Telegram - only bots responding to the user's request, the phone number is not available to the bot.