At a customer site, running a Baracuda firewall, iPhone users were unable to check for devices updates. Everytime the user would have iTunes check for device updates it would fail. One of the rules in the Barracuda is to allow iTunes updates.  The rule to allow iTunes updates was enabled, but the traffic was still being blocked. I monitored the weblog and found the iPhone version check was being blocked by a streaming media filter. I added a URL pattern to allow access to and iPhone update traffic could get through the Barracuda.