Set up Your Network for VoIP

Do the users in your company use the 8x8 Work for Desktop, 8x8 Work for Mobile, or physical IP phones on their desks? Knowing the answer helps you concentrate your efforts on your wireless or wired network.

The more you know about your network, the better prepared you are to properly integrate VoIP. Start from your local network to your WAN.

• If users are serviced via wireless network, make sure you have plenty of access points (AP) to service all corners or workplaces, and that the Wi-Fi access points are not overloaded. When moving from Wi-Fi AP to a different AP, the hand-off must be performed properly.
• If users are using physical phones, or if the workstations are serviced via wired network, make sure you have all prioritization for voice traffic over data.
• Review current WAN bandwidth levels, traffic flows, and existing switches for bottlenecks and choke points. Then, identify or determine specific needs through testing and modeling. This helps you identify any trouble points or bottlenecks in your network.

There are a variety of metrics you can use to assess 8x8 call quality, including jitter, MOS, R-Factor, gap density, burst density, QoS prioritization, and compression techniques.

Implement QoS for the ingress and egress data traffic on your network, and ensure all LAN devices adhere to it.

Organize your VoIP and data traffic by VLAN groups, in order to resolve issues more easily.

Ensure there are no issues with these three Key Performance Indicators (KPI), as they represent the highest impact to your call quality. Many times these KPI issues are caused by external upstream carrier issues that may require you to open tickets with your Internet service provider. Bufferbloat is high latency in packet-switched networks caused by excess buffering of packets. Bufferbloat can also cause packet delay variation (also known as jitter), as well as reduce the overall network throughput. When a router or switch is configured to use excessively large buffers, even very high-speed networks can become practically unusable for 8x8 voice traffic. Some communications equipment manufacturers placed overly large buffers in some of their network products. In such equipment, bufferbloat occurs when a network link becomes congested, causing packets to become queued in buffers for too long. In a first-in first-out queuing system, overly large buffers result in longer queues and higher latency, and do not improve network throughput.

For comprehensive understanding of your network traffic, capture and store network data before implementation, shortly after deployment, and again a month or so after deployment. With these three data sets, you can spot data trends in the performance of your network. Baselining validates 8x8 performance, helps future capacity planning efforts, and gives you a long-term understanding of your 8x8 service.

Headsets can vary in price and performance considerably. The best headset for your situation varies based on whether desk phones or softphones are being used, and on the environment they are being installed in (such as the level of background noise). Some people prefer the freedom of wireless headsets, though it usually comes at a considerable price premium. In addition, the battery life of wireless headsets must be considered, as they are not primarily designed for call centers where they are in use all day. PC headsets have the further consideration of their connectivity mechanism, such as USB or headset jack. Headsets which connect using a headset jack typically lack the features of more advanced USB headsets, which may have built-in noise reduction and echo suppression. If you use headphones with headset jacks, the minimum specification for the PC sound card must include echo suppression. Telephony headsets are usually more expensive than their PC equivalents, though not always with any justification. When buying headsets for desk phones, check whether the phone actually has a dedicated headset port, as without a port, the headset also needs a separate amplifier. 8x8 has no particular recommendation for which headsets to use.

8x8 recommends that ALG be disabled on all your network gear, as it is known to cause the 8x8 solution to not perform correctly. For details on ALG and possibly solutions for disabling, please refer to the Disabling SIP-ALG in Your Router or Firewall.

Enabled ALG on your edge device or other network gear is the most likely cause of failed phone registrations. This may be represented in the device that simply fails to register altogether, or intermittently loses registration. The failed registration may also be caused by ports 5060-5061, 5196-5199, and 5299 being blocked.

Assuming the phone is registered, a lack of audio can be caused by a number of problems:

• If you are not using a headset, make sure that the headset is operating, the volume is turned up, the microphone mute button is not selected, and the headset is not engaged.
• If you are using a headset, it is recommended to test with a handset or speaker to ensure the sound issue is not headset-related.

While using 8x8 Work, go to Settings > Audio and Video; you can verify that there is audio transmitting being received using the indicator bars, and that the proper audio device is selected. You can also use the 8x8 audio quality testing service, which allows you to speak a short phrase, records it, and plays it back to you.

For Polycom phones, however, go to Menu > Status > Diagnostics > Media Statistics in the phone to see the packet information. During an active call to see real-time information about your call, use the packets transmitted (Tx Packets) to see this number increase rapidly when speaking; this indicates the phone is receiving audio and sending out to the network. The receiving (Rx Packets) indicate that packets are being received by the device; if this number increases when speaking, then the issue is most likely with the handset, cord, etc. If this number does not increase, the usual suspect would be a firewall issue or ALG. These issues can also be identified by testing with the 8x8 Network Utility tool.

Gaps in sound occur when jitter exceeds 8x8’s recommended maximum of 20 ms, packet loss exceeds 0.3%, or both. Depending on how delayed the packets are, you may experience robotic sound as the Codecs try to interpret what sound must be played for the missing data. If the packets are completely lost, no sound plays, since the number of missing packets exceeds the approximation.

Phone echo is caused by signals bouncing back from analog phone lines (only two wires). Echo cancellation in digital equipment must detect transmitted sound that is received back, and cancel it out.

In addition, make sure that users lower their microphone gain as much as possible. If the microphone is far from the mouth, the software driver compensates by raising the gain, which causes echo when it picks up sound vibrations from the earpiece on boom microphones. Ideally, you must first turn off any auto gain feature, as it can cause gain to go up and down during the call, and then you should set up with a test call.

If echo is still experienced, it is possible that the latency on the connection to 8x8 exceeds the recommended maximum of 100 ms.

Voice (real-time) communications are very sensitive to latency and variation in packet arrival times. 8x8 requires steady, dependable delivery receipt of voice packets to provide excellent call quality. Packets arriving too early, too late, or out of sequence result in jerky and jumbled communications. This phenomenon is referred to as jitter.

Because no network can guarantee a perfectly steady stream of packets under real-world conditions, 8x8 uses several patented and unpatented technologies to help combat any normal and expected jitter that is part of a real-world network; it is only when this jitter starts to exceed our recommendations that you experience an issue.

Jitter is usually calculated using packet timestamps instead of RTP timestamps. To calculate jitter, you can use the 8x8 Network Utility, or using your Polycom phone, go to Menu > Status > Diagnostics > Media Statistics during an active call in order to see real-time information about your call (or the last call you made if tested in an idle state).

Note: 8x8 recommends that jitter be less than 20 ms, with a latency of no more than 100 ms.

Packet loss can be the result of the jitter buffer being overwhelmed, LAN or Internet issues, or poor wireless signal quality. The latter can be a big problem with Voice over Wi-Fi service. Regardless of the source, 8x8 phones and gateways attempt to conceal this type of signal degradation by patented and unpatented methods. As with jitter, these techniques can maintain voice quality only to a point.

Packet loss on data networks is usually characterized as a burst phenomenon. Networks tend to either sporadically drop single packets (these periods are called gaps in packet loss), or large numbers of packets in a continuous burst. Packet loss concealment techniques typically have no problem handling packet loss during gap periods; it is the sustained bursts you must watch out for. Analytics for 8x8 Work helps to identify these differences.

Note: 8x8 recommends that packet loss be no more than 0.3%.