You could, but Noonlight uses many phone numbers.
Noonlight uses a pool of phone numbers to contact users in the event of an emergency. There is not just one number to save, and the pool of numbers can change often.
As of 4/21/2021, the current list of numbers for Noonlight are:
But what if my phone blocks Noonlight as a spam caller?
In the event of an emergency, keep your phone close. Noonlight will contact you almost immediately if an alarm is triggered and isn't disarmed by your PIN before your Entry/Exit delay has passed.