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Record on-the-fly for your extension - click the grey record button to the lower-right corner of your name.
Screenshot showing the record button
Record other's calls - click the red recording button under their name. The button is only shown when they're actively on a call.
Recording is a permission that must be configured under the Web Admin Panel -> extensions -> group (permissions) tab.
Please read Permissions Definitions for detailed instructions about the permissions system.
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See the various HUD Agent / Call Center Edition features in action. This video is only a few minutes long. I recommend showing it to your employees, or e-mailing them the link and instructing them to watch it.
HUD video tutorial for the Call Center