How connect to Q2686 MIC and SPK pin analog telephone?


#1

I’m developing an audio interface to convert the 4 wires of Q2686 gsm module to 2 wire audio line to connect a standard telephone (standard GSM Gate).

I use standard telephone and connect his mic in and spk out to spk out and mic in Q26. But there are echo in remote mobile station. Why?

Can you hlep me with interfacing standard analog phone to GSM module Wavecom ?

I hope, that it´s standard aplication, but I dont find some app notes or schematic for this interface…

Thanks,

Best Regards,

Jan Půhoný


#2

I have the same problem, when you put GND comunun in the SPK, then the audio returns generated by the MIC echo, I believe that Wavecom is ineffective for this application proved better with ENFORA or SIM340 that does not generate echo.