This app will allow you to send SMS alerts from Splunk without using Internet connection.

The app allows to send text messages from your Splunk instance directly to 3G/4G network using SMSEagle. SMSEagle device sends SMS directly to cellular network. There is no third-party external services between. This ensures full security and privacy of information shared across your IT infrastructure. And your SMS will get through even if your Internet connection fails.
How to use it?
1) Get your SMSEagle 
2) Insert your SIM card into SMSEagle 
3) Connect SMSEagle to your IT infrastructure
4) Configure the app in Splunk 

Now you can send SMS alerts from your Splunk instance directly to 3G/4G network.