Snom 220 - Manual (Page 14)

Logon
14
By choosing a different line, your originator phone number is changed to
this line. This means that different people can start calls from the same
phone with their own originator phone number and the called phone will
display this current outgoing line information. The current outgoing line
is marked on the idle screen with a black-colored phone icon in front of
the registered SIP line.
DND Mode on/off
Independent from Logon Wizard settings, the DND functionality is
available in the snom menu. DND is short for “Do Not Disturb”. If this
mode is activated incoming calls will no longer come through to the
phone and you will be completely undisturbed by the phone. If there is
a mailbox set up for you, the call is redirected to it. Before this mode is
activated, you will be asked if you really want to change to this mode.
In idle mode, “DND active!” is displayed in the bottom left-hand corner
of the screen when DND is activated.
Challenge/Authentication
In SIP, a user can also set up authentication requirements for each
registration on the phone. The password for each account name can be
set up via the web interface of the phone in Lin1-7 / Login Information /
Password.
If the authentication password is not set, or set wrongly, the account
will not register on that domain and the phone will be challenged for
that line. A challenge response will ask for the correct password. This
can look like: