Call button voltage measurement: Use a multimeter to test the two lines of the call button. Normally, there is no power. A relay should be installed if there is electricity.

Call button is good or bad measurement: When the call button is pressed, use the multimeter resistance to measure the two lines of the call button are on. If not, it may be that the button is bad and needs to be replaced.

After the above check is correct, the call button line can be connected to the corresponding switch contact of the car speaker. 

Note: When checking the elevator accompanying cable, it can be found according to the number on the two signal lines of the machine room and the car box, saving the time of checking the line.