Lack of sound or poor sound quality
Lack of sound is typically due to blockages in your firewall or errors in your broadband router. Poor sound quality is almost always due to poor internet connection.
Crackleling or choppy sound
This is typically a sign of too little bandwidth or packet loss on your broadband connection. If you hear cracks, it's your downstream speed and if others hear them, it's your upstream speed, which is usually the problem.
Is your internet connection good enough?
Virtually all internet connections in developed countries are so good that they can be used with IP telephony without any problems. Try our test and read more
- Check RTP settings
If you have Cisco, Linkys or Sipura equipment, make sure "RTP Packetsize" is set correctly according to our guides.
- Close programs that generate traffic
These can be file sharing programs, viruses (remove), etc. that send data to the internet. (See also point 5).
- Check for packet loss
At a command prompt (Start -> Run, then type "CMD" and press [ok]. Enter: "ping -t voice.redspot.dk". Let it run for a minute or more. Stop the test with CTRL-C. Package loss must be 0%. Measure at the times when there is the most load, which is typically between 18.00 and 20.00 on weekdays. Contact your provider if the value is above 0%.
- Check your bandwidth
See the section "Is my internet connection good enough?" above.
- Use Quality of Service (QoS)
Use a router or adapter that supports QoS and can prioritize your voice traffic.
- Change your CODEC settings
Typically, the G711 is also called ULAW / ALAW / PCMU / PCMA by default in your adapter or phone. This CODEC provides the best sound quality, uses the most bandwidth and is therefore sensitive. Read more about CODEC's under "Frequently Asked Questions".
Solution, Linksys and Sipura
Under "Line 1", "Audio Configuration set
Preferred Codec: "G729a"
Use Pref Codec Only: "Yes" (only if you use Clearwire *)
*) A few IP phones do not support G729 and you will thus not be able to talk to people who use these, including Xten X-Lite. In addition, you may experience problems with calls to IP phones that forward to voice mail.
Select G729 or iLBC as the first priority or option. In Counterpath X-Lite 2.0, deselect a CODEC by clicking on it in the display so that it turns light gray.
It is impossible to fax via anything other than G711A / U. However, Cisco, Linksys, and Sipura adapters will normally recognize fax calls and automatically switch to the G711. Choosing CODECs with compression (all other than G.711A / U) also carries a greater risk of echo.
Read more about CODECs under "Frequently Asked Questions".
Help Topic HT040053. Published 26 August 2004. Updated 12 September 2023.