Dear All & Benny, I am using simple_pjsua to do the call test. There is no sound device on my board. I set the sound device to null sound device. But now I try to play a PCM file and make remote client can heard the PCM data. My question is as below 1: Should I put the PCM file reader code in null_put_frame() (in null_port.c) and send PCM data to conference bridge? Is that a correct way? 2: How can I send PCM data to conference bridge and make put_frame() (in conference.c) can put the data to do the decode/encode Thanks for your help!!!!!!!!!!!!!!!!!!Thanks!!!!! Duncan -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20100112/398b1c0a/attachment.html>