You can click on this link from your phone. http://pbxyz.com/download/cellgateway.apk and it will download the app.
You then get a popup to open the app. Or, go to your Chrome browser downloads and find the file.
Click on the file “cellgateway.apk” to execute the install.
Your android phone’s Chrome web browser will scold you “For security you are not allowed to install from unknown sources.” It will also provide a settings link
Click the settings link, and set “Allow from this source”
Hit your back key to find the file and click to install.
You get a App installed check mark.
Use the app!