The Telco Sentinel is a bi-directional DTMF to ASCII transceiver. It converts DTMF to ASCII and ASCII to DTMF when connected to a telephone line. The unit is also equipped with a electronic hybrid providing send and caller audio on both 3.5mm jacks, along with removable screw terminals. Data interface to a PC is via a USB port. When transmitting DTMF strings, delays between digits can be inserted in 100ms increments. A post-transmit delay of 0.0 to 9.9 seconds can be added that will cause a delayed transmission of tones after the string is received on the USB port. Tones are transmitted at a selectable speed of 50ms, 100ms or 500ms tone/space. Tone transmit buffer is 256 characters long. There is an adjustable ring count for answering the phone line of 1-9 rings or 0 for no answer. Front panel send and caller telephone line audio trimmers are supplied, along with front panel LED’s display; power, ring, hook and tone. The unit derives its power from the USB port.