Samsung 08/2004 - Manual (Page 86)

Network services
85
Caller ID
You can prevent your phone number from being
displayed on the phone of the person being called.
Note: Some networks do not allow the user to change
this setting.
The following options are available:
Default: the default setting provided by the
network is used.
Hide number: your number does not display on
the other person’s phone.
Send number: your number is sent each time you
make a call.
Active line
Some SIM cards may be used with two subscriber
numbers. This functions is available only if your SIM
card supports it.
This menu option allows you to select the line to be
used to make calls. However, calls can be answered
on both lines, regardless of the selected line.