Phone and Voice Quality
We have solutions to correct VoIP echo, choppy voice, broken voice, buzzing and delayed speech. These common descriptions of VoIP problems with a VoIP connection are the direct result of some other factor. In most cases, these quality issues result from a few identifiable causes. Follow these correcting steps and the quality of your calls will show a marked improvement.
Echo in telephony systems is caused by two main phenomena: the first is acoustic echo due to microphone pickup of audio. The second is electrical echo due to mismatched impedance. Although both sources will produce similar effects, they can be easily distinguished from each other. Electrical echo is a property of the line connection and will typically continue constantly throughout the conversation. Acoustic echo varies in both strength and delay and will vary depending on the changing source conditions of the echo itself.
How to correct VoIP echo:
The number one cause of echo is from voice traveling out from the earpiece or speaker back into the mouthpiece or what is referred to as acoustic echo. Turning down the volume of the phone can greatly reduce this cause for echo. Another cause of echo is electromagnetic interference. This can be the result of positioning the IAD (your VoIP device) too close to other electronic devices, such as, on top of the computer or near the back of the monitor, or right next to a power strip. These three devices have particularly large electrical fields and should be given extra attention about positioning so they will not interfere with other devices. But, other devices can also create electromagnetic currents, so it is best not to place the IAD and/or any base station of a cordless phone too close to other devices. Poor quality splitters, phone cables and other devices between the phone and the ATA can introduce echo due to "bounce back", caused by impedance variations. Poor wiring, including longer lengths of untwisted cabling (wire), wet or damaged cabling, and poorly terminated cables will cause echo and crosstalk. Cheap phones can also be the cause of echo, and not just with a user at that phone, but throughout the premise. Using cordless phones, can also introduce echo, sometimes the result of outside interference. To correct echo try these steps:
- Hold your hand over the mouthpiece. If the echo subsides then turn down the volume of the phone. *You should actually keep the volume turned fairly low regardless, as VoIP connections are extra sensitive and you will experience better quality by doing so.
- Move the IAD away from other electrical devices.
- Remove any splitters or separate caller ID devices between the IAD and the phone. In many cases this can cause echo that you hear on your end.
- Try using another phone cord, as some phone cables can be of poor quality.
- If you are using a cordless phone try to replace it with a corded phone (connected directly to the IAD and see if the echo stops.
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For a more technical explanation of VoIP Echo and how it relates to PSTN networks see our VoIP Technical Tutorial.
A second cause of echo on a VoIP connection can be the result of poor echo cancellers either at the IP-PBX, at the destination speaker or poor to non-performing cancellers is the carrier network. Typically, gateways, either cards in an IP-PBX or at a hosted providers server have both hardware echo cancellation modules and software algorithms that provide echo cancellation.
- Improperly configured echo canceller algorithms (software) on the IP PBX or no echo cancellation chip (hardware echo canceller)
- Problems with an acoustic echo canceller on the destination speaker phone (This would result in an echo much like the result of a speaker phone feedback, but would occur across the LAN between two phones in the same location).
- Nonperforming echo cancellers in the carrier networks gateways.
- Improper settings on the TX Gain and RX Gain.
Solve VoIP choppy voice:
Choppy voice or broken voice on a VoIP connection is usually an issue with insufficient or unavailable bandwidth. A typical two-way conversation takes about 90kbps on both the upload and download on a G711 codec. (There are other, more compressed codecs that can reduce the required bandwidth, G729 being a popular one.) In some cases you could have enough bandwidth from your ISP, but a computer application is grabbing the available bandwidth, essentially taking it away from the VoIP transmission. Usually bandwidth issues result in brief dead spots in the conversation, sometimes described as a stutter or a staccato sound.
- Try turning off all your computers to see if the issue still occurs.
- Test your bandwidth, both upload and download.
- Check for file sharing software, these programs usually run in the background and use your bandwidth to upload files.
- Check your computer for malware and Spyware.
- If your router has QoS, then enable it for your VoIP connection. Linksys BEFSR41 now has QoS. [How to enable QoS]
For a step by step approach to fixing broken voice on VoIP.
You can do an Upload and Download Bandwidth Test.
Your bandwidth should not be continually less than 80% of your ISP's subscribed level of service. If it is, then you should have your ISP's technical support look at your connection.
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Typical bandwidth* usage for different codecs.
- G711 - 87.2kbps -This is the best quality codec.
- G729 - 31.2kbps -A compressed good quality codec.
- G723.1 - 21.9kbps -The codec best for satellite, (more compressed).
- G726 - 55.2kbps
- G728 - 31.5kbps
*These figures are the nominal Ethernet bandwidth one-way and are only for the voice traffic on a single call. To calculate how much bandwidth would be required you will also want to consider internet use by computers and other devices. (Also, remember a three way call (two parties called), will take twice the nominal bandwidth.)
Broken voice with suffcient Bandwidth
If your system is experiencing periods of broken voice and other quality issues and the WAN network is good, then there could be another possibility. It could be duplex mismatches occurring between devices. This possibility would typically be for larger IP-PBX systems where there are several devices including the phone switch, a managed switch and the gateway router. One device will set the duplex speed and another device will have a setting that mismatches. This will create packet loss, becoming worse and worse until a reboot will temporarily correct the issue. And it really could be a reboot of one of several devices, as it will then allow the device to sync back up correctly. But, this will only last until the next occurrence, when it will happen again. Take the following steps:
- Hard code each device's Duplex settings so they match and do not allow a setting of Auto-negotiate. This would need to be set for the IP-PBX, the switch port, and the WAN router interface.
- Configure QoS to prioritize voice connections on your router.
Hard coding settings in some devices so they will always match may eliminate some sporadic quality issues.
For more VoIP Voice Quality issues and how to solve them.
(Buzzing, Static and interference in VoIP calls.) Continue