Getting and injectingan audio signal at the same time from/to phone

thingmaker3

Joined May 16, 2005
5,084
Make sure your device has a characteristic impedence of 600 ohms and a bandwidth of 300-3300 Hz . Make sure it can withstand 90Vac ringer voltage on the signal line. If it is to run off the phone line voltage, make sure it runs on 48Vdc.

Then simply connect it in parallel with the phone line.
 
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