Introducing 3rd party interfaces.
There are various ways as how Nagios can be managed, one of the ways is to integrate it with 3rd party apps or interfaces and enhance its scalability.
These 3rd party interfaces can be used to send notifications via sms, mms to mobile phones etc.
There are a wide variety of choices available at Nagios exchange -:
Nagios community is the same which contains various plugins and additional interfaces for Nagios.