@Margi1
You need to download the Airbnb phone app to your phone to be able to respond to enquiries.
What is happening at the moment Margi you are getting a message alert on your phone but, that alert is coming from the generic side of the Airbnb program! The message will be incomplete and you can't respond to it! It is simply an alert that you need to respond to from your Airbnb profile, nothing else.
What you need to do is follow this link and download the appropriate app for your phone system, be it Android or Apple.
This link will take you to the official Airbnb app....
https://www.airbnb.com/mobile
Make sure you allow the app to fully download and if the download should stop part way, delete it and download again.
Once you have dowloaded this app you will have almost full functionality on your phone. You will be able to perform most functions that you currently can on your computer. The only things you will not have access to are sensitive account information which you will still need your computer to access and change.
I hope this helps you.
Cheers.....Rob