Need to be able to use your phone as a drop-in replacement for a pager? Do you need support for MMS as well as SMS? Would you like to have your phone silenced except for your alarm clock and pages? Then this is the app for you.
For SMS, the application looks at both the sender and the message. For MMS, it only looks at the sender.
The pattern that you want to set is either a phone number in the case of an SMS or an e-mail address in the case of an MMS. The application does not try to look at your contact list.
For example, suppose that you get an e-mail from "firstname.lastname@example.org" via MMS. You would simply put "email@example.com". If you get a text from 555-867-5309, you should set a pattern like "5558675309".
For SMS messages, you can also match on text. For example, if you see something like "Sev 2" in your SMS messages, you could set that as your pattern.
Once you have configured a pattern, you can simply close the application. If you get an SMS or MMS that it thinks matches the pattern, then it will pop up a notification on your phone.
Note: I no longer have an Android phone, so I can only provide limited support at this time. The open source project page is here, and pull requests are welcome: https://github.com/billatq/beeper
Note: This doesn't work with Google Fi or with FreedomPop. Both of these services bypass the system API for receiving messages. For more details, see the third-party app note here: https://support.google.com/fi/answer/6211316?hl=en