2013 Toyota Sequoia Owners Manual - Page 427

3-5. Using the hands-free phone system (for cellular phone) Type B Volume The voice guidance volume cannot be adjusted using this button. On-hook switch Turns the hands-free system off/ends a call/refuses a call Off-hook switch Turns the hands-free system on/starts a call Talk switch Turns the voice command system on (press)/turns the voice command system off (press and hold)