I won't recommend you to play with Telegram. You will be in trouble if you have Telegram when going to US. Telegram was used by the terrorists for communication.
One major problem Telegram has is that it doesn’t use end-to-end encryption by default, something the FBI has advocated for. “There are many Telegram users who think they are communicating in an [end-to-end] encrypted way, when they’re not because they don’t realize that they have to turn on an additional setting,” Christopher Soghoian, Principal Technologist and Senior Policy Analyst at the American Civil Liberties Union, told Gizmodo. “Telegram has delivered everything that the government wants. Would I prefer that they used a method of encryption that followed industry best practices like WhatsApp and Signal?