Refer to page 19 of the M1 Installation Manual for steps to create a “Custom Recording” which uses a house telephone as a microphone to create an open air recording. Another option might be to use the ELK 120 Recordable Voice Driver in conjunction with the ELK 129 Sound Card Interface to load a Wave File into the ELK 120 and then use a voltage output from the M1 to trigger the ELK 120 to play the message.