Draytek Vigor2820 Series User Manual page 180

Region Select the proper region which you are located. The common
settings of Caller ID Type, Dial tone, Ringing tone, Busy
tone and Congestion tone will be shown automatically on the
page. If you cannot find out a suitable one, please choose
User Defined and fill out the corresponding values for dial
tone, ringing tone, busy tone, congestion tone by yourself for
VoIP phone.
Also, you can specify each field for your necessity. It is
172 Vigor2820 Series User's Guide