headphone jacks

Could you post how the terminals are connected...
The 4 terminals on one side are probably 2 separate coils.If so you may connect your phone line to one coil and the soundcard line-in(or line-out) to 2 terminals on the other side.
Please post details of the terminals...

I measured the impedance of the transformer using the multi- meter and one side i got the impedance around 48 ohms ( which I used for the Telephone side) and on the another between the middle and either one I got the impedance of around 86 ohms ( which is used for the PC side).and I used the the RC schematics with zener diodes what has been given this forum is working fine.

But on the telephone side the audio what Iam getting from PC is very much low. and even i tried with RC Coupled audio amplifier circuit on the telephone side but i didn't work out. Can anyone tell me how can I amplify this audio signal on the telephone side.

I measured the impedance of the transformer using the multi- meter and one side i got the impedance around 48 ohms ( which I used for the Telephone side) and on the another between the middle and either one I got the impedance of around 86 ohms ( which is used for the PC side).and I used the the RC schematics with zener diodes what has been given this forum is working fine.

But on the telephone side the audio what Iam getting from PC is very much low. and even i tried with RC Coupled audio amplifier circuit on the telephone side but i didn't work out. Can anyone tell me how can I amplify this audio signal on the telephone side.

Regards
Sanath
Bangalore

Try reversing the connections ie. telephone on the 86 ohms side and pc on the 48 ohms side...
Ideally a 1:1 transformer should be used.