I had this same problem over the weekend. Since I fixed it remotely, I am not sure which of the following actually fixed it. 1. I completely uninstalled Manager and deleted all the text and scr files in the Manager folder. 2. I re-installed Manager, 3. then deleted the VoIP extension ID's of the affected users. Only delete the extensions, not the User. Reboot the IPO, and created new VoIP extension for those phones. This gave them new extension ID's. 4. reboot again. The phones connected and did a firmware upgrade and are working this morning. I would start at step 3 first and see if that fixes it before removing Manager...
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