To send outgoing messages via telegram and messenger channel is different from WhatsApp. You should have list of contact first on your channel. Hence, your clients need to reach out to your telegram bot or Facebook page to have listed on channel. Sending broadcast to new recipients is not possible through these two channels.

Once you have list of numbers

• Go to broadcast
• Click new broadcast
• Set up your broadcast including the name, timing (send broadcast instantly after finishing set up or send at scheduled time), broadcast channel, broadcast message, attachment
• Then, select recipient (existing clients)
• Check your broadcast message and recipient once again.
• Click send and that’s it!