Skydeck Caller ID is strictly opt in. Launch Skydeck on your phone and go to the Settings option on the menu to enable it.
If you do not have Skydeck installed on your phone, or you do not see a Settings option on the menu, download the latest version of the application. Open the browser on your phone and go to http://m.skydeck.com. (If you are upgrading from a previous version you may have to reboot your phone.)