In case you receive a notification on your tablet or smartphone that it isn’t compatible with mysms (although you own an actually supported device), make sure you download the right app for your tablet or mysms mirror (they differ from the regular phone app):

• Open the Google Play Store on your tablet/smarpthone and search for “mysms tablet” or "mysms mirror"
• Try to download the app directly from these links: Tablet app, mysms mirror.