Connect audio source to standalone landline phone?

Thread Starter

rudyauction8

Joined Jan 27, 2012
250
I am trying to connect an audio source to a wireless landline phone set. It is not connected to an actual land line, I need it to work on its own transmitting audio from the audio source connected to its phone line to its handsets. Don’t need it to ring, just need to know how to trick the phone into thinking it has a line connected to it. Found tons of info online about on splicing into a working phone line, none relating to what I’m trying to do.
 

Thread Starter

rudyauction8

Joined Jan 27, 2012
250
A long, long time ago I hooked a 3.5mm aux cord directly to a phone line with no other mods or parts and it worked fine, no luck this time. Wondering if this set looks for the isolation transformer or something else.
 

SamR

Joined Mar 19, 2019
1,133
Look up Phone Patching. It's used for patching a Ham Radio's audio into a phone line. Might be of some help.
 

Ylli

Joined Nov 13, 2015
760
A POTS phone operates on a current loop of 20 mA. Nominally, it has an impedance of 600 ohms, so off-hook you should see 12 VDC across the line. On hook (open circuit), I believe the system battery was 48 volts. Ring is nominally 90 VAC/20 Hz.
 

Dodgydave

Joined Jun 22, 2012
8,356
50V DC in UK off hook, drops to around 20V when picked up to answer, ring tone is pulsed DC at approx 2 to 20HZ.
 

Thread Starter

rudyauction8

Joined Jan 27, 2012
250
Looked up phone patching and was able to rig up a 14.4v lipo pack through a resistor and isolating transformer and get my phones working. Thanks
 
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