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Wireless Connections

While not all-encompassing, the issues reviewed here are some of the most often encountered when troubleshooting a VOIP WiFi problem. The impact of home and enterprise environments equally and are important to rule out when facing issues with VOIP on a WiFi network.

Physical Obstructions

Wifi is a radio signal, and as such, is subject to interference due to physical obstructions. Listed below are some frequent physical obstructions and their impact on radio signals, including wifi.

  • Metal, concrete, and stone - will block most signals completely
  • Drywall - little to no interference to wifi signals
  • Glass - will bounce the signal back, which can make the signal look strong while delivering low throughput, or slow speeds.
  • Wood - the impact of wood depends on the type of wood in question.
    • Thin, or softwoods like Balsam or compressed wood - little interference to wifi signals
    • Hardwoods like Oak - will absorb the wifi signal, degrading strength and throughput

Physical obstructions can be difficult to factor into your WiFi setup, but it is important to know how much they can impact your network. If you are having problems with VOIP, think of an imaginary line from your device to your WiFi router. If there are any of the materials with a high impact to radio waves between them, or a lot of windows bouncing the signal around, then you will need to move the WiFi router or your device to get a better signal.

Channel Congestion

Another factor in wifi strength and dependability is traced back to the amount of congestion on the channel used. While most modern routers are supposed to scan the local channels and use the one with the lowest number of networks, this is often implemented poorly and does not work as intended.

The best way to ensure you are not being impacted by the surrounding wifi radios is to use a scanner to determine if you are on a channel that is used by a number of other networks. This can be accomplished by using the scanner software built into your router, if it is accessible, or using a third-party application like “WiFi Analyzer” to check the local channels.

A congested channel can be identified by a high number of other networks on the channel or a couple of other networks that are very strong on the same channel. This means that even if you only have two other networks on the same channel, but their signal strength is as strong as, or stronger than yours, you will experience interference.

If you determine you are on a congested channel, most routers will allow you to manually set the channel you would like to use. This process alone can vastly improve your network.

Electromagnetic Interference (EMF)

While physical obstructions are an important variable to factor when troubleshooting WiFi, appliances with strong electromagnetic fields can be just as damaging to WiFi performance. The impact the signal by scattering the WiFi radio waves when they interact. Effectively creating an invisible wall that blocks or degrades the wireless signal. EMF interference is also sometimes referred to as Radio Frequency (RF) interference.

It can be difficult to Identify this form of interference, but there are applications that will assist. In your mobile device app store, you will find many Electromagnetic field (EMF) detectors that use the built-in sensors on your device to identify strong fields emanating from an appliance. Using the application, scan the appliances between your device and your router to identify problems.

Once the offending appliance is identified, you will need to determine if the appliance, your wireless device or your WiFi router needs to be moved to correct the issue. In some cases, it can be as simple as moving your laptop to a different location.

WiFi Protocols

A network impact often not addressed is the WiFi protocol being used. Currently, in the US, this includes 802.11a/b/g/n/ac. Almost all wireless antennas, worldwide, are only capable of using one protocol at a time.

If all devices are using the same protocol, meaning all devices are 802.11ac or 802.11n, then there is not an impact on connectivity. However, if even one device on the network is using 802.11g, then all devices are forced to connect with the less reliable and lower throughput 802.11g protocol. This causes the newer devices to lose the option to use the better protocol, impacting connectivity, and communication.

To avoid the issue, determine the protocol your VOIP device uses and ensure that all devices on the network will be using the same protocol. Relegate any devices, not on the required protocol to the frequency band (2.4 GHz or 5 GHz) you are not using for VOIP.

Frequency

All of the previous information should be considered when determining which frequency to use for your wifi connection. They are especially important when using a VOIP solution, as VOIP is much more dependent on both a solid connection and fast communication than most internet applications. The 2.4 GHz and the 5 GHz ranges are available to most users. While many believe that the newer 5 GHz is always best to use, both have their own advantages and disadvantages.

Something to remember is the lower the band, the greater the range, but the lower the capacity. Some of the considerations for each frequency band are:

  • 2.4 gigahertz
    • Longer range
    • Less vulnerable to interference
    • Slower speeds
  • 5 gigahertz
    • Shorter range
    • More vulnerable to interference
    • Faster speeds

This means you will need to review all of the potential impacts on your network like EMF, physical obstructions, protocol, etc to determine the best frequency to use.

Band Steering

Band steering is implemented on many newer routers with dual-band WiFi. A dual-band router is a router that supports both 2.4 GHz and 5 GHz. It encourages clients able to use both bands to use the 5 GHz band to connect. This allows the older, 2.4 GHz band to support legacy clients unable to connect to the 5 GHz band.

If you have a router that supports both 2.4 GHz and 5 GHz but you only have one SSID, then you are using Band Steering. The SSID is the name of the WiFi network to which you are connecting.

While Band Steering is great in a lot of situations for basic internet applications, it can cause issues when used with VOIP. While the 5 GHz band has greater capacity, as we have highlighted in the rest of the article, it may not always be the best connection. VOIP requires both a strong connection AND good capacity. So you will need to take all of the factors of your network into consideration before implementing Band Steering.

Bandwidth Calculations

To ensure the best possible voice quality, we recommend using either any high-speed DSL, Broadband, or Fiber-optic connection. With a minimum dedicated upload and download bandwidth of 100 kilobits/sec for each voice line, you plan to run.

Routers, Switches, and Firewalls

Dialpad does not require a specific brand or mode Router, Switch or Firewall, to ensure the highest possible quality of service, the Network hardware should have the following capabilities:

  • QoS
  • Bandwidth Limiting
  • SNMP

We also recommend checking that these following features are turned off. Please contact our support team if you are unable to turn off these features:

  • SIP-ALG
  • Deep Packet Inspection (DPI)
  • Stateful Packet Inspection (SPI)

Multiple Internet Circuits

If you are utilizing multiple internet circuits, a best practice is to set them up as Primary/Failover. Please contact our Support Team for any questions.

VPN

Dialpad is not designed to function over a VPN. If your company uses a VPN, please utilize a split tunnel and direct Dialpad traffic outside of the VPN.

VLAN

A virtual LAN (VLAN) can be used to put your hard-wired phone devices into separate networks, and to manage security and routing policies separately. If you plan to deploy IP phones, they can be placed in a “voice VLAN”.

A voice VLAN is not a network requirement for Dialpad service but best practices for setting security, DHCP, routing, QoS/CoS a voice VLAN may be used.

Note:

Setting a voice VLAN is required when Workstations are daisy-chained through IP Phones.

QoS

Enabling QoS will depend on your router and its capabilities. The following are general guidelines based on protocol and port, along with a basic priority level (highest, high, low, etc.).

Specific rules will better define the traffic rules, eliminating erroneously flagged packets as being a high priority.

Routers may allow QoS to be defined based either on application (RTP/SIP), or allow QoS to be defined on application and port (RTP over UDP), or allow on destination port, or any combination of Application, Source/Destination port. Dialpad’s Voice traffic is flagged with DSCP markings:

  • DSCP 46 = RTP Traffic
  • DSCP 26 = SIP Traffic

FQDNs

Routing to an FQDN or Fully Qualified Domain Name, allows modern Cloud Networks flexibility for Routing, Security, System Maintenance and remote Device management.

Dialpad uses FQDNs for:

  • Register
  • Exchange SIP to set up call
  • Manage Device Firmware
  • Manage Device Configurations
  • Remote Device management

Dialpad recommendation as a best practice to whitelist traffic to/from each of the following FQDN:

Ports and Protocols

Port and Protocols used by Dialpad phones and applications residing in private network are listed below. Outbound port configurations are needed on the Firewall to allow traffic to the Destination Ports listed in the right-hand side column of the tables. Stateful Firewall is recommended for Dialpad deployments. For Stateful Firewall, inbound port configurations are not needed as they are automatically opened as a reply to the outbound traffic.

Desktop Native & Browser Applications:

Dialpad Mobile Application

Obihai Desk Phones

Polycom Phones