Originally AT&T released OS for the Blackberry Bold, but decided to yank it once the OS was reported to have conflicted with AT&T’s network. The original release was maintenance bundle 508, but the new one is 517.

Here is the e-mail that was sent from AT&T:

NEW BlackBerry Bold Maintenance Release v4.6.0.517 now available
BlackBerry Bold Maintenance Release bundle version
(comprising application version v4.6.0.297 and platform version is now available for customers to download.  Bundle 517
contains all the functionality of the recently-removed bundle 508, but
addresses the software issue affecting the interaction between the
device and network enhancements being deployed.  There are no
additional changes in bundle 517 (as compared to earlier BlackBerry
Bold MR bundle 508) other than addressing the software issue.  For a
review of the added functionality contained in this release, please see
the original communications for BlackBerry Bold Maintenance Release.
Customers who downloaded bundle 508 should upgrade as soon as they are
able as bundle 508 contains the software issue that is addressed in
bundle 517. Customers on earlier versions (bundle 298 and maintenance
release bundle 438) should be made aware of the performance
enhancements and added capabilities of bundle 517 and should be
encouraged to certify and upgrade their users.
Bundle 517 Maintenance Release is available for customers to download though 2 means:

  • Over-the-air delivery via OTASL (For information see “FOTA For BES
    Administrators” on the BlackBerry Enterprise Product Page in OIL)
  • Download from  www.att.com/bbdownloads

Visual Voicemail provisioning has also been re-instated for customers who have upgraded.