May I suggest that your listing of the available voices…:
…be made to correspond with (namewise, even if not as complete as), the one you link to…
…where users can listen to audio samples. Without that, it’s a bit unclear which Voices your “Male 1”, “Female 2”, etc. correspond to, unless one inspects the calling URL more closely (i.e. “Female 2” == ‘en-US-Standard-E’).
You may also want to remind users to include their Country Code (especially people in the U.S. who won’t think to type ‘+1’ before the Area Code), without which the API will timeout.
UPDATE 1: I’ll leave all this up for others who try poking around before the actual instructions get posted (at which point I will remove this Reply!). Please note that the registration process will require a Telegram Messaging username, so you might want to get a jumpstart installing that (free) app and selecting a username before all the good ones get taken, lol.
UPDATE 2: Everything works awesomely once you get a Telegram ID.
PRO TIP: Windows users may want to install the Telegram Messaging applet on their PC as well, in order to receive CallMeBot call directly in their browser!