2010 ADA Standards for Accessible Design Pocket Guide
Call buttons shall have visible signals to indicate when each call is registered and when each call is answered.
EXCEPTIONS: 1. Destination-oriented elevators shall not be required to comply with 407.2.1.5 provided that visible and audible signals complying with 407.2.2 indicating which elevator car to enter are provided.
2. Existing elevators shall not be required to comply with 407.2.1.5.