Skype for Business - enable QoS on your network

Most small to medium businesses will be using Skype for Business phones (and software clients, on smartphones or within a browser) on the same network as their computers and tablets. Those computers and tablets may be consuming large portions of bandwidth, downloading updates, uploading documents to the cloud, and so forth. Therefore, it is vital to implement QoS on such networks to ensure audio and video receives priority when the network under contention. Here's a quick guide...

Step 1: ensure that your Skype for Business Online is actually logging and analyzing call quality

• Log onto http://potal.office.com as an Administrator
• Naviagte to the Skype for Business Admin Centre
• Select the Skype for Business Online Call Quality Dashboard
  • Here's the direct link: https://cqd.lync.com/spd/#/Dashboard
• Once logged in, logging is activated automatically

Step 2: implement QoS in your router

Differentiated Services Code Point (DSCP) is a protocol for ensuring Quality of Service (QoS) on your network. IP packets inbound/outbound can be tagged to ensure certain traffic gets priority.

Assured Forwarding (AF) tagged packets guarantee a certain amount of bandwidth

Expedited Forwarding (EF) is used to build a low loss, low latency, low jitter, assured bandwidth service

The industry standard settings are: EF46 for voice, AF41 for video

Your router should be set to tag packets as type EF46 for traffic in/out of the following Skype for Business ports:

UDP 3478, 3479, 3480, 3481

Optional: UDP/TCP 50,000-59,999 (these ports were used on devices with firmware/clients older than 2017, so you may need to support these ports too)

Also, Skype for Business uses TCP ports 80 & 443 but these are common with computers and tablets that may be downloading. For example, if you have iPhones on WiFi a 100+ MB iOS update will be downloading on port 443! Therefore, the only way to prioritise Skype for Business traffic on port 80 & 443 will be to specify the source/destination IP addresses (or FQDNs) - if you have the time and inclination, the currently maintained list of IP addresses and FQDNs is available here: https://support.office.com/en-us/article/Office-365-URLs-and-IP-address-ranges-8548a211-3fe7-47cb-abb1-355ea5aa88a2?ui=en-US&rs=en-US&ad=US

(We do not believe it is pragmatic for most small businesses to devout time to maintaining firewall rules in their router for port 80 & 443)

Step 3: verify that your router is actually prioritizing the traffic

There are several tools to analyze your network traffic. We use WireShark, although this does require some investment of time to become familiar with the tool. Several Microsoft Technet contributors have outlined ways of testing that require modest technical experience; one excellent blog was contributed by Matt Soseman https://blogs.technet.microsoft.com/skypehybridguy/2016/07/23/validate-qos-for-skype-for-business-online/

If we are supplying you with your Office 365 licenses, then we'll be able to assist you with this step (if you're not yet subscribing to Office 365 via us, then Why not? We do not charge above the direct Microsoft price and you get the benefit of Microsoft Support plus Support from us!)

Additional steps

You probably have remote workers, home workers and VPNs. Any remote locations will also benefit from configuring their routers to implement QoS. Some routers, especially residential equipment, may not support QoS - you may need to invest in upgraded hardware.

Finally, ensure that clients (IP desk phones, apps, browsers) are up-to-date with the latest firmware and updates - Microsoft work with providers to share performance updates regularly.