Centracom II / II+ DPI Card Primer

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A description of the CCII/II+ Direct Phone Interface circuit card.

Centracom Direct Phone Interface BLN6872
An Informational Primer on Centracom Phone Patch

The Centracom DPI (Direct Phone Interface) card permits interfacing of a Centracom Central Electronics Bank (CEB) to the Public Switched Telephone Network (PSTN).

The DPI uses a standard POTS (Plain Old Telephone Service) telephone line. The line is plugged into the DPI at P3, an RJ11 jack located on the front of the card.

The DPI card is actually a daughtercard that physically attaches to a host BIM card. The host BIM must have special firmware installed on it in order to support the DPI.

The DPI card hybrid line connection is by way of a MRTI RLM-3 line interface module that is mounted on the DPI. When all said and done, there are actually three circuit cards stacked together to make a complete DPI: The host BIM, the DPI, and the RLM-3.

DPI allows patching of the radio system to a telephone line. On the console, the telephone circuit appears as another available radio channel, with the exception of the DPI Channel Control Module (CCM) not having a volume pot.

DPI radiotelephone interconnect is [b:347b0fd43e]NOT[/b:347b0fd43e] an automatic function controlled by user DTMF. It requires operator intervention at the console in order to setup and knockdown the patch.

The DPI can also be used for placing and receving phone calls from the console without use of the patch. The DPI CCM has an "Off Hook/Ringing" button/LED combo, a hold button, a release button, and LED indicators for status as well as the channel patch buttons.

Dialing DTMF on the DPI CCM is accomplished by sending a "Touch Code" page over the DPI CCM: Pick the line up at the console on the DPI CCM by depressing OFF HOOK. Press MANUAL ENTRY, then TOUCH CODE, and select the DPI CCM. Dial the telephone number on the Radio Control Panel (RCP), and press SIGNAL/TALK. This encodes the DTMF on the DPI CCM and sends it down the telephone line.