This is a smart app that allows you to check values from your Thingspeak channel. In this app you can enter lower and upper limits so that when the value is outside the range sms can be sent to your chosen contact. This can be used in real scenarios-
1. You have a heart monitoring device that measures BPM. You enter the limits(specifically 60-100) and your device records a value that is outside the given range. Immediately sms is sent to your contacts alerting them of your high/low BPM.
2. You have a smoke detecting device. You open the app to check the smoke level in your house. If you see a high value then sms is sent and your contacts(mainly neighbours) are aware of a possible fire in your house.
3....and many more.

In short,this is the app you will be needing.

ThingSpeak is an open source "Internet of Things" platform to store and retrieve data from things using HTTP over internet. With ThingSpeak you can create sensor logging applications, location tracking applications, and a social network of things with status updates. For more info please visit https://thingspeak.com.