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Telulog was a project I built some time ago to log outgoing telephone calls originating from �loop disconnect� (pulse dialling) telephones. I�ve no doubt it could be readily adapted for use with DTMF (dual tone multi frequency) instruments if a suitable DTMF decoder were to be substituted in the PSTN interface - something that I�ve never managed to get round to doing. Of course the device should never be used �for real� as it is not �approved� for use, but it makes for an interesting concept model all the same. Another thing that may require alteration is the lack of digits in the display. Of recent years we�ve seen change after change in our telephone numbering scheme, making the 12 digits - (I thought adequate at the time!) possibly not enough today. If, however, a number greater than 12 digits is dialled, the unit simply �looses� the overflow and only records the first 12. The device keeps a software TOD clock running, and logs each number dialled (to a reference 001, 002, 003 etc.) then the time the call was made along with the duration in minutes and seconds. All this information is stored in a non-volatile RAM chip. (An ordinary low power RAM fitted into a powered �smart� socket) |
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