GSM 2 shield no sound on audio out

GSM 2 shield,

SMS receive and transmit working perfect, make voice call, makes the call perfect, but I don't her anything (both sides of the connection, arduino and cellphone). For receive a voice call it is working also ok, I her the incoming call on my earplugs and the connection is made, but again no sound (both sides). I use a earphone and microphone from my iPhone, also with a normal headset at both sites of te connections there is also no sound. I use the standerd programs from Arduino. I hope you can help me. Greetings Pieter.

Has anyone solved this? I have exactly the same issue. I hear the ring tone of the GSM shield, but as soon as the connection is opened there is no sound.

This has been solved, the issue being that you need to changle the audio channel on the GSM Module -> https://forum.arduino.cc/index.php?topic=400927.0