SkyBell HD doesn't require an activation code and will automatically broadcast it's ID during the sync process.
If you are attempting to sync a SkyBell HD, and the app requests that you enter a 24 digit device activation code, you are using the SkyBell 2/Classic App. Please download the SkyBell HD app and start the sync process again. Please click here for complete SkyBell HD sync instructions.
There is also the possibility that you have a Version 1 or Version 2 SkyBell classic. In this sync process you will be asked for your activation code. You can locate the device activation code on the back of the SkyBell faceplate on a white sticker, on the instructional booklet and on a sticker on the box that the SkyBell was sold in.
SkyBell HD app for iOS devices: SkyBell HD
SkyBell HD app for Android devices: SkyBell (black icon with green writing)
SkyBells Version 1 and 2 app for iOS devices: SkyBell Classic
SkyBells Version 1 and 2 app for Android: SkyBell for Android