If you are an experiencing audio quality issues such as metallic echo or silence then there is possibility that some of the RTP ports have been trapped in old sessions and that the PBX considers these ports as free ports and continues to send them traffic.
When a new call is made then RTP ports are assigned to the call for audio stream if the assigned ports have already got stuck somewhere then PBX may assign the same ports to new call which will cause audio problems because used ports are not free ports for the audio stream.
To check whether RTP packets are causing voice quality issues you can check the text log by going to VOIspeed Server –>Advanced configuration –> log folder. Open the latest log text file and search for the string RTP Remote IP/Changed Port.
This is an example of a warning message:
Warning: ProcessRtpAudioPacket -> RTP REMOTE IP\PORT CHANGED – from 192.168.150.117:4002 to 192.168.150.227:4870
The IP range in a message shows the IP of connected phones and devices. If the log shows many similar messages which are repeating with in a second then you need to note down the repeating IP address as this is may be the IP address of the phone or device linked to an unresponsive port.
Once you find the IP address of the device, then simply turn off the device and turn it on again and check whether that resolves the problem. In some cases the metallic audio issue could be due to the overheating of the device. If so, please make sure that you place the device in a cooler environment.