How to get something transmitted to your iphone once engaged?

For example the house alarms in a common household, some have features to connect to your phone as a warning sign. How is this done, what kind of transmitter etc. Say if you had a lock system on a 2nd house in cornwall. Lots of distance with no Wi-Fi. Just battery.

Apple store

Its called a Client application that you download on your Smart Phone

Your house is configured with Hardware and that Hardware contacts Server for a bunch of reasons… Sometimes you need Internet Access already in your Home or the Hardware may have a modem inside of it which contacts their Server directly.

That Server contacts the appropriate Clients… But those must have Internet connections.

My son's house alarm sends SMS messages both to him and also to me when the alarm is triggered. It is connected to his domestic phone line and waits for the line to be idle before calling the message centre to send a message. The home phone line should be idle when the house is empty and the alarm is set.

Cellular phones can receive SMS (text) messages while they are actually on a voice call.