Quality of Service (QoS) refers to a set of techniques and technologies used in computer networks to manage and prioritize traffic. The primary goal of QoS is that Zoom Phone traffic gets preferential treatment over less time-sensitive traffic (e.g. file downloads, video streaming, etc.) in your network, which provides a better experience for phone calls.
Zoom Phone is a cloud-based phone system that routes traffic over the public internet. It's essential for customers to have sufficient data connectivity to avoid voice traffic degradation, although this can be costly. Alternatively, customers can use Quality of Service (QoS) markings as outlined in this document to prioritize Zoom Phone traffic over less latency-sensitive traffic for the best possible connection.
Note: This setting is disabled by default and must be enabled by an administrator based on your network’s requirements.
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A successful implementation of Quality of Service (QoS) in the network requires careful planning. QoS is important in an enterprise network environment where traffic congestion may affect media quality and lead to a poor user experience. For users to have a great experience when using Zoom Phone, the following must be considered:
Quality of Service (QoS) manages traffic prioritization during network congestion. An effective strategy to prevent congestion involves provisioning ample bandwidth for Zoom traffic. When planning bandwidth requirements, it's crucial to anticipate the volume of concurrent calls at a site during peak business hours. This planning allows network administrators to plan for adequate bandwidth provisioning to support Zoom Phone traffic during peak periods without any quality degradation. Each Zoom Phone call uses between 60 and 100Kbps of data.
For instance, in a location where 100 users collectively engage in 30 concurrent calls during peak hours, the necessary bandwidth for Zoom Phone is calculated at 3000 Kbps (or 3 Mbps). This figure is determined as follows:
100Kbps X 30 calls = 3000 Kbps
Planning should also account for other data traffic sharing the same network so sufficient bandwidth is allocated without compromising voice quality.
In situations where increasing bandwidth may be cost-prohibitive, customers can utilize QoS to prioritize voice traffic over non-real-time traffic. This prioritization helps maintain a consistent user experience despite bandwidth limitations.
It should also be noted that ad-hoc conferencing on the Zoom Workplace app may involve more than one active voice stream per call. In these cases, it is crucial to have sufficient additional bandwidth for Zoom to facilitate these ad-hoc conference calls without quality degradation.
Delay refers to the time taken for media packets to travel from the customer’s network to Zoom's data centers and back. Voice traffic is particularly sensitive to delays that can degrade quality beyond acceptable levels. Zoom has implemented multiple mechanisms to maintain quality even when there are significant delays. However, round-trip delays should not exceed 300ms to ensure optimal performance.
Jitter refers to the variation in packet arrival times when packets arrive on the Zoom Workplace app. When the variation in packet arrival times increases, this could cause poor call quality.
Packet loss refers to the loss of data packets as they travel across different networks. As Zoom Phone operates as a cloud-based system, its traffic travels over the internet and may encounter packet loss. Zoom has implemented measures to mitigate the impact of packet loss on voice calls, but it is advisable to have minimal packet loss so voice calls can have a satisfactory call quality.
Zoom Phone supports the use of DSCP (Differentiated Services Code Point) markers to prioritize traffic, which is particularly useful in scenarios with limited bandwidth. This marking enables customers to identify and prioritize Zoom Phone traffic across their network. When implementing QoS, it's crucial that these markings are honored and preserved as traffic traverses the network.
However, it's important to note that once traffic leaves a customer's network and enters the internet, DSCP markings are typically not preserved. Internet traffic is generally treated as best effort, and internet providers do not prioritize traffic based on markings. This distinction is critical when prioritizing traffic from the Zoom data centers that are coming from the internet over a corporate network and terminating on the Zoom Workplace app.
Therefore, organizations should carefully plan and configure their QoS policies to effectively manage and prioritize Zoom Phone traffic within their network boundaries, considering the limitations and behaviors of internet traffic outside of these boundaries.
Wireless networks are crucial for providing an optimal user experience to Zoom Phone users who depend on Wi-Fi connectivity. Besides implementing QoS on wired networks, meticulous design and planning of wireless infrastructure are essential for effectively managing real-time voice traffic. Wireless vendors typically advocate best practices for deploying voice over Wi-Fi, incorporating techniques such as Wireless Multimedia Extensions (WMM), packet scheduling, and traffic prioritization. These strategies enable consistent high quality and reliability for voice calls over wireless connections.
Additionally, in scenarios where Zoom Phone users move within a wireless network, it is advisable to implement seamless roaming mechanisms. These mechanisms enable devices to transition between wireless access points smoothly and reliably, minimizing disruptions and promoting continuous connectivity and call quality.
In some instances, organizations may implement VPNs to facilitate access to corporate applications. However, VPNs inherently introduce packet overhead and can introduce delays in real-time traffic. To maintain optimal performance for Zoom Phone, it is advisable to enable split tunneling and refrain from routing Zoom Phone traffic through the VPN. Customers can refer to the provided IP address list to configure exclusions accordingly. This approach helps mitigate the impact of VPN overhead on Zoom Phone traffic for consistent and reliable communication.
Zoom Phone is a cloud-based phone system, which means its traffic travels over the public internet. Typically, any DSCP (Differentiated Services Code Point) markings set by the Zoom Workplace app are lost when traffic passes through the public internet. DSCP policies configured through the Zoom admin portal only apply to traffic originating from the Zoom Workplace app and directed towards the Zoom cloud. Traffic originating from the Zoom cloud towards the Zoom Workplace app will not retain any DSCP markings.
To manage this, customers should consider adding DSCP markings at the edge of their network using existing network devices capable of marking traffic before it transits the internal network. One option is to use the source ports utilized by the Zoom Workplace app to facilitate easy identification and marking of traffic if necessary.
Note: Customization of source ports from the Zoom admin portal is only available for the Zoom Workplace app. For desk phones, consult the appropriate vendor documentation to get the source port range parameters and optionally use provisioning templates to deploy the changes in bulk. The following resources offer guidance for Zoom Phone-certified desk phones:
When implementing QoS on your network, it's important that the implementation be done end to end. Partial implementation of QoS in a network may lead to unpredictable results. To assess how your network is performing, Zoom has provided the following tools:
Zoom allows setting DSCP markings for Zoom Phone traffic. To set the appropriate markings, customers should ensure implement the markings that are decided end to end on the corporate network. The DSCP markings set on the administrator portal should align with what will be honored and preserved on the network for a successful deployment.
To enable or disable Enable QoS with DSCP marking for all users in the account:
The settings in the Zoom admin portal enforce the Zoom Workplace app to mark the Zoom Phone media and signal traffic to the values specified. The following considerations should be taken into account so the values can enforce the settings appropriately.
In specific scenarios, there may be a need to classify traffic based on ports. Zoom Phone on the Zoom Workplace desktop and mobile apps utilizes UDP ports 9000–9999 for outbound traffic. If customization of these source ports is necessary, you may have to select source ports to use during a Zoom Phone call. It's important to use the correct values in the provided examples for proper configuration and operation.
Note: Customization of source ports from the Zoom portal is only available for the Zoom Workplace desktop and mobile app, Zoom Phone Appliances, and Zoom Rooms.
By default, Windows does not permit the Zoom Workplace app to configure DSCP markings on outgoing traffic. However, the Zoom Workplace app utilizes the Windows native API to assign the following DSCP markings:
For the above settings to be effective, the corresponding values must be configured in the Zoom admin portal.
In cases where the above values need to be modified, the following methods are available:
The Zoom Workplace app running on mobile devices (Android/iOS/iPadOS) or Linux/macOS will apply the DSCP values that are set on the Zoom admin portal. Typically, no additional privileges are required for setting the DSCP markings configured on the Zoom admin portal, but this may vary based on your environment.
Zoom Phone supports DSCP marking for VDI plugins. For a successful deployment of Zoom Phone, it is recommended to have the VDI deployment in Direct Optimized mode whenever possible. This allows the Zoom Phone media to originate from the VDI plugins and the signaling from the VDI clients.
When the QoS policy for Zoom Phone is turned on from the admin portal, these settings are applied to the VDI client and plugin, respectively. If the VDI client or plugin is installed on a Windows machine, the steps outlined in the “Windows Zoom Workplace app” section will apply.
Note: The registry keys available to set DSCP markings for Zoom Meetings are not available for Zoom Phone.
Zoom Phone allows DSCP markings that are defined in the Zoom administration portal to be pushed down to certified devices. Learn more about the list of certified devices that support this functionality.