5120 - Telephone Line Monitor

By sensing the voltage present on the telephone line it detects and measures ringing, DTMF & pulse dialing, FSK (Bell 202 and V.23) signals, line polarity reversals, and open switching intervals (OSI). Working in conjunction with the TRsSim software on a PC, the 5120 becomes a valuable tool in analyzing and debugging Caller ID and SMS (Short Message Service) data transmission.