What is the exact role of the "url_launcher" Package and which packages allow calls/SMS to be made via the Internet Connection?

HELLO Again.

I would like to understand if this “url_launcher” Package can make it possible to call and/or send SMS only on the “Wi-Fi” Internet network without being billed by GSM mobile telephony networks ???

Otherwise, how to create a call and SMS application working only on Wi-Fi with the “Flutter” Framework and not requiring payment to GSM networks, that is to say a Call and Send Flutter Application 100% FREE SMS via Wi-Fi ???

Do you think this is exactly what the “url_launcher” package does in Flutter ???

Thank you in advance for your lighting.