No audio is heard by remote party
Check that microphone is functioning properly by looping-back microphone to speaker device.
Check that no other application is using the sound devices. It is common to not be able to use sound device when other application is using the device.
Check that the microphone is connected to the call in the conference bridge
Check that audio is transmitting and to correct remote address.
Use pjsua on the remote side to check that packets are received. Follow Check if RTP packets are received on how to use pjsua to verify receipt of incoming RTP packets.