You can use Catalog Bar mobile app while in offline mode.
Open the catalog in your mobile and click on the menu icon on the top right of the catalog
You can see the “Offline Mode” button on the drop-down options
When you click on the “Offline Mode” button, the app will download the files from the catalog to your mobile
When the downloading is completed, the app will show you the “All file download completely” dialog box as shown in the image below
All the files will be saved in your mobile memory.
You can update or book the sales order as soon as you are back in online mode.