@peterdrake https://www.ekiga.org/ is an open source telephony app based on open protocols
SMTP (aka email)
@Pat @marcorobotics If he doesn't have notifications turned on, he might not see it for hours. If he does, his device would never stop screaming.
Maybe there's a way to set up notifications for only certain messages...
In fact, I would not be surprised if some email clients already have that capability built in.