Basic IM App for Android

I would like to have a custom instant messaging app created for Android. This app will only be used by 2 people to communicate privately via their Cellphones. Here is the list of features I need: - The ability to send text messages between 2 people (no emoticons, images, etc) - The icon for the app should not show in the app drawer, you should dial a number to run the app, like #7328 - The app should prompt the user for a password (this can be pre-configured and fixed) - The app should have some generic name like "Network Monitor" - The app should support offline messages, so that the person still receives a message that was sent to him while offline. I do have various websites and/or databases available to use for this project. This of it as a very basic version of WhatsApp or Wechat, but just for 2 people to communicate in private using text messages only. I've never requested an Android app to be written, so please let me know if you require additional information.