Hi, I come across with a problem when I change the PJSIP_MAX_PKT_LEN value (increase/decrease) in config_site.h file, I will not get any information from pjsip_rx_data. When there is packet coming in, on_rx_request() will notify the application with the pjsip_rx_data has a length of 0 in msg_info and there is no info in msg_info.buf. In addition, I have put more debug info into the pjsip source code and found in pjsip/src/pjsip/sip_endpoint.c function pjsip_endpt_process_rx_data() is handling the rdata and make the callbacks in this code. 883 if (msg->type == PJSIP_REQUEST_MSG) { 884 do { 885 if (mod->on_rx_request) 886 handled = (*mod->on_rx_request)(rdata); 887 if (handled) 888 break; 889 mod = mod->next; 890 } while (mod != &endpt->module_list); 891 } else { 892 do { 893 if (mod->on_rx_response) 894 handled = (*mod->on_rx_response)(rdata); 895 if (handled) 896 break; 897 mod = mod->next; 898 } while (mod != &endpt->module_list); 899 } I verified that before the callback the rdata actually have a valid and correct msg_info. While rdata pointer still matched with the pointer before and after callback, the msg_info changes to all 0 when executing the callback function. Is this a known issue in PJSIP? Or is there something wrong with my change? I do need to increase PJSIP_MAX_PKT_LEN in order to send out larger SIP packets that is larger than 4000. Otherwise, I will get the message is too long error as most folks already reported before. Your help is greatly appreciated. Justin