Telegram should be avoided. They do weird things with their security and ignored criticism on it. The key verification requires checking an image, so you can't do it over the phone. Plus closed source, so you're very likely entirely depending on trusting Telegram.

Their response to using AES IGM? It's along the lines of "yeah this strange mode no one uses has issues but not in the way we use it so whatever. We've got math PhDs, so trust us."

I'm no expert, but I get a really bad feeling about them, since it's the totally wrong attitude to take.