Thanks Nanang for you answer! By "impossible", I mean that the file contains only silence. The file is not empty because its size is few hundreds of Kio for few tens of seconds. And for call, no sound for the addressee. My pseudo_code is the following for a recorder: pjsua_recorder_create(&filename, 0, NULL, 0, 0, p_id); pjsua_conf_connect(0, pjsua_recorder_get_conf_port(*p_id)); And the following for a call: pjsua_call_make_call(acc_id, &uri, 0, NULL, NULL, ¤t_call); pjsua_call_get_info(call_id, &ci); pjsua_conf_connect(ci.conf_slot, 0); pjsua_conf_connect(0, ci.conf_slot); Regards, R?my.