Dear alls, I install pjproject version 2.8 on ubuntu 18.04 physical machine with sound card, my program is implemented with Pjsua2 and it works well. It can play sound and record caller speech. Once I install pjproject version 2.9 on EC2 ubuntu 18.04, and set inbound UDP ports 5060-5061, 30000-40000, run program with calling setNullDev() function. It can only play sound but it does not record caller speech, it records silent audio file instead. I cannot get answer from Googling or Pjsip FAQ, so please advise. Best regards, Paksasoft <https://www.facebook.com/paksasoft> .........................................................