I am new to this community. I don't know if my question is On topic or not. I am dealing with a GSM modem. This is a kind of modem which works exactly like our phone. It is mainly used for call dialing, messaging and other applications similar to our phone. It works on AT commands. The modem has separate pins for mic and speaker indicated by
MIC_N MIC_P for
SPK_N SPK_P for
speaker. I have connected below speaker and mic:
Now the problem is whenever I am on a call, it echoes back my voice through speaker. There is not connection between speaker and mic because for them different pins are available. What could be the reason for echo.?