Existing Android Application with offline Google Maps

I have developed an android application, which takes coordinates from a web interface (google map) and plots the route on the android application (google map). Now, i want these google maps on android application to work in offline mode (no internet available). The task is to download the offline maps on the device of a certain city and plot the route on the offline map. the coordinates for plotting the route (from one location to another) will be coming via SMS from the web server on the android device. SMS is already being received on the device, you just have to download the map and plot the route on it in offline mode for whatever coordinates are coming from web. application is developed in eclipse.