The MT500SR2
Dialed digit monitor will detect, store and display DP,
DTMF, MF, SF and E&M signaling. Displays 32 characters
with error indicator. Audio speaker. RS232 parallel
printer port. 310 jacks. Power is -48 VDC and 115 VAC with
-24 VDC optional. Single rack space, 19/23". Weighs 5 lbs.