Developers try so hard these days to implement push notifications from their apps & services and boast about all the IFTTT stuff.
Carries here in India used to provide email-to-sms as a free service. You would just send an email to +91PhoneNo@xyzprovider.com and that message would be sent to PhoneNo as an SMS (160 chars from subject).
Now a days if you want to send a message, you need to have developer accounts, install Software on the devices to receive the notifications, need to have a data connection on the phone, talk to push notifications clouds and a few other things.