Telegram Basics
Official telegram.org Source
One check— message delivered to the Telegram cloud and your friend has been notified if he allows notifications.Two checks— message read (your friend opened Telegram and opened the conversation with the message).
We don't have a 'delivered to device' status for messages because Telegram can run on as many devices as you want. So which particular one would that check mean?
Official Telegram Reference: https://telegram.org/faq
Part of the TGWAY.com Official Telegram Knowledge Base (98 Verified Q&As).