From Sprints web pages Link
"Last Updated: Sep 27, 2011
Just like your computer, your phone's software needs to be updated periodically to make sure you have all the latest fixes and enhancements to keep it running at optimal performance. Follow the steps below to check your current version and perform any needed updates.
Version History
Current Version: 2305.13.40301.651
Version
Date released
Description of enhancements/fixes
2305.13.40301.651
(Note: This update will only be available via the Zune Software client on your personal computer. The software update will be pushed to your HTC Arrive after you connect your phone to a PC with Zune software installed. To download the free Zune software, visit http://zune.net/support.)"