Sorry it took awhile to get back. The reason why the second port didn't show up in CCA User Extension tab is that currently only phones with assigned extensions will display. In the 'show ephone reg' showed that the second port did not pick up an auto assigned extension-
You probably have "auto assign 10 to 19" configured under telephony-service. What I suspect happened is that ephone-dn 10 to 19 is already assigned to phones (ephones) on your UC500. When you plugged in your ATA and it attempted to auto register the second port it was able to pick up an ephone but not an ephone-dn. Since the second port did not have an extension assigned to it, CCA will not display that in the user extension tab.
We're currently looking into this further to see what we can do to address this.
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