I read in the manual where you can "easily install the upgrade key" to expand beyond 4 sip phones. Where do you get the key? Do you have to pay for it? Got a pn?
The SPA9000 supports up to 16 phones. The user manual has not been updated.
As long as the firmware version of your SPA9000 is 5.1.9 or later, there is no license key, or any additional steps needed.