You should provide the following information when you submit a new issues to Sangoma:
- Description of your problem
- Procedure that explains how to reproduce the issue
- TGZ or ZIP file containing the folders: /usr/local/ntg/log and /usr/local/ntg/conf
Having a capture of the network traffic between the endpoints and NTG is the simplest way to diagnose audio issues. Unfortunately NTG does not provide a mean to capture the network traffic to a file. But here are 2 recipes that could be used to perform the capture.
The first recipe consists to simply use off the shelf Network Analyzer software like Wireshark to tcpdump to capture the traffic from the 2 endpoints who are having the audio issues. This recipe works as long as you can run this type of software on system where the endpoints are running.
The second recipe consists to install an Ethernet hub between the primary media and eth1 (assuming that you using eth0 for your SIP traffic) and follow these steps:
- ssh to the NTG box
- example: ssh root@<ntg-ipaddress>
- Configure eth1 in promiscuous mode
- Make sure eth1 as not IP address
- Enable interface in read only mode
- ifconfig eth1 up
- Capture the RTP and SIP traffic to a pcap file.
- tcpdump -i eth0 -i eth1 -w my_capture.pcap -s 2048
- Make your call
- Make sure you have the audio issue
- Hangup your call
- Enter Ctrl-C when the call is done
- Transfer my_capture.pcap file to a PC where you can analyse the capture
Once you have the network capture, you can use a Network Analyzer software like Wireshark to read and the decode the SIP and RTP messages. Run VoIP analysis on make the following varifications:
- Make sure the IP addresses advertised in the SDP of the SIP messages transmitted to NTG are reachable by NTG.
- Make sure the RTP packets transmitted to NTG are using the payload types advertised in the SDP.
- Make sure the RTP packets transmitted by NTG are using the payload types advertised in the SDP.
When the call is established successfully and there is no audio or one way audio issues the problem is often caused one or more of the following reasons:
- Trying to use NTG with devices behind NAT or a firewall. This is is not supported,
- IP addresses advertised in the SDP of the SIP messages transmitted to NTG are not reachable by NTG. Make sure NTG can reach the IP addresses advertised in the SIP messages.
- The RTP packets transmitted to NTG are not using the payload type advertised in the SDP.