AT&T Merlin Legend MLX-10 User Manual page 21

Your MLX-10 Telephone
Phones with SA Buttons
SA Ring. Use this button to make and receive both inside
and outside calls. To call an inside number, dial only the
extension. For outside calls, dial a dial-out code (usually a 9)
before the phone number.
SA Voice. Use this button to make inside voice-announced
calls and outside calls and to receive both inside and
outside calls. Voice-announced inside calls do not ring—
your co-worker hears your voice over the speakerphone
instead. To make outside calls, enter a dial-out code (usually
a 9) before the phone number.
1-8 Line Buttons