Problem you'll run into with scanning bar codes displayed on mobile phones - it won't work. In general, barcode scanners can't scan digital screens for barcodes.
Unless they don't use typical barcode scanners. I'm thinking photo recognition scanners - they point the camera on their smartphone at the screen of the barcode to be scanned; the app sends the decoded data to the server and gets a success or denied along with ticketholder info (name, etc)....
I just had my iPhone "scanned" at MSP at security as my boarding pass... So it's doable.