I replaced other parts of an old cellphone with an old landphone. I replaced the ear piece with the landphone ear piece. But when tried to connect the microphone to cellphone mic connection its howling or echo. So I experimented with stereo headset with wires. But same prob repeating. Actually I want to use that spring type wire to connect for giving a superb genuine landphone appearance. Spring cable contains 4 wires and connecting through their teleponic ports. Help me to connect and correct my microphone.

 

And this is homework for which course????

 

And this is homework for which course????

Haha.................

 

The problem is that the hardware and software are carefully crafted and tuned so that they do not interfere with each other. By changing one or both mic and speaker you are changing the tuning characteristics