Yes, you can scan tickets without an active Internet connection. However, a few things you should keep in mind:
1) You will need to download the ticket data to the device before you can start scanning. To do that, just connect the device to the Internet, click on the event, and the data will synch from our servers.
2) If you don't have an internet connection and you are using more than one device for scanning, the devices will not be able to synch. The result is that a ticket will be able to be reused and scanned on multiple devices.
3) If you don't have an internet connection and you sell more tickets after you have downloaded the ticket data, the ticket data for the newly issued tickets will not be on the device. Therefore, those new tickets will not be able to scan until internet connection has been restored, at which point the devices will automatically sync with our servers and the new ticket data will download.