Hi Anne, This is my config_site.h content: #define PJSIP_MAX_TSX_COUNT 31 #define PJSIP_MAX_DIALOG_COUNT 31 #define PJSUA_MAX_CALLS 4 #define PJSUA_DEFAULT_CODEC_QUALITY 4 #define PJSUA_MAX_ACC 4 #define PJSUA_MAX_PLAYERS 4 #define PJSUA_MAX_RECORDERS 4 #define PJSUA_MAX_CONF_PORTS (PJSUA_MAX_CALLS+2*PJSUA_MAX_PLAYERS) #define PJSUA_MAX_BUDDIES 32 Please try pjsytest on your ARM board if you hear somethings or you can record your voice (Note: copy all the input.*.wavs audio files on the same path of pjsytest). I hope this help you. Regards, Paolo.