Samsung SCH-R530MBBUSC - Manual (Page 85)

Calling 79
Other Call Settings
Ⅲ From the Call settings screen, under Other call settings,
and configure the following options:
• Auto retry: When enabled, your phone automatically redials a
call if it receives a busy signal from the network.
• TTY mode: Choose a TTY mode to enable TTY mode, for use
with optional TTY equipment.
• DTMF tones: Set the length of Dual-tone Multi-frequency
tones, that play when you use the keypad during a call, such as
when navigating phone menus.
• Voice privacy: Enable or disable enhanced voice privacy, to
improve the security of your phone calls.