How to register the Gigaset C300H & CS3 Additional Handset:
1 On the main phone base (the one connected to the phone socket), press and hold the paging button for 5 seconds until the base beeps. The base is now in registration mode.
The next steps must be finished within 60 seconds.
2 On the handset you want to register, please press the right side of the navigation button, the handset will enter the main MENU.
3 Using the navigation button scroll down the options until you come to "Settings" and then press "OK".
4 Scroll down again using the navigation key until you come to "Registration" and confirm your selection by pressing "OK".
5 Press "OK" again to confirm that you wish to register the handset.
5 The handset will display the message 'Handset is registering', which can take up to 1 minute. If prompted to enter the Base PIN, the default is 0000.