The Telephone Consumer Protection Act (TCPA) is a law that was passed by the US Congress in 1991.  This law places restrictions on telephone solicitations and the us of automated telephone equipment, protecting the public from receiving unwanted phone calls.

While schools enjoy exemptions from some of these restrictions, the preference configurations within the SchoolMessenger App allow you to set your consent state ("yes" or "no") for each phone number associated with your account.  With the exception of emergency calls, which cannot be exempted, any phone number whose consent state is set to "no" will not receive calls from SchoolMessenger.