All calls and messages in the messenger will be sent only when the Internet is connected? What is the speed of the Internet for the stable operation of the application?
Definitely, without an internet connection, the messenger will not be able to perform its functions. 1 megabit / sec is enough for chat
The operation of the application depends not only on the speed of the Internet connection, but also on the ping.
I hope that the application will work stably even at low Internet speed
LTE is already running almost everywhere, which allows speeds of up to 50 Mb / s.
I think this will be enough for any application functions.