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Teams Call Quality Basics: Fix Choppy, Robotic, or Dropped Calls
"The phones sound robotic." "Calls drop after a minute." "They can't hear me." Almost every Teams call-quality complaint in a small office comes down to the network, the device, or the one user who's on a hotel Wi-Fi with a VPN. Here's how I'd work through it, in order, with the Microsoft tools that show you what actually happened on each call.
Match the symptom to the likely cause
Microsoft's network guide links these symptoms to causes (Prepare your network for Teams):
| What people say | Microsoft's likely cause |
|---|---|
| Teams is slow | Not enough bandwidth |
| Calls keep dropping | Firewall or proxy blocking |
| Static, cutting out, robotic voices | Jitter or packet loss |
Step 1: Look at the actual call
Don't guess. In the Teams admin center, go to Users, pick the person, and open the Meetings & calls tab. Microsoft says it lists the calls and meetings the user took part in over the last 30 days. Select one to see detailed media and network statistics, including the devices, network, and connection used (Use Call Analytics to troubleshoot poor call quality). Microsoft says Call Analytics shows each leg of a call, so you can see whether the problem was this person's side or the other end.
For trends across the whole office, Microsoft's Call Quality Dashboard is under Analytics & reports > Call Quality Dashboard in the Teams admin center. Microsoft says an admin with "Activate CQD" privileges has to sign in the first time (Set up Call Quality Dashboard).
Step 2: Check bandwidth
Microsoft lists audio calls at a minimum of 10 kbps up and down per endpoint, 58 kbps recommended, and 76 kbps for best performance. Video and screen sharing need much more. Microsoft also says that when bandwidth is short, Teams prioritizes audio over video (Prepare your network for Teams). In my experience, audio alone rarely fills a small-office connection. When it sounds bad, something else is usually saturating the line, like backups, large uploads, or video. For a fuller estimate, Microsoft's Network Planner in the Teams admin center calculates requirements from your locations and usage.
Step 3: Fix the firewall basics
- Allow Teams media over UDP. Microsoft lists Teams media at UDP ports 3478–3481 to its published Teams IP ranges, in the "Optimize" category (Microsoft 365 URLs and IP address ranges).
- Keep URLs and NAT clean. Microsoft says to allow all Microsoft 365 URLs, and that your firewall shouldn't change the mapped NAT addresses or ports for UDP (Prepare your network for Teams).
- Keep Teams off the VPN. Microsoft recommends split-tunnel VPN, so Microsoft 365 traffic goes directly to Microsoft instead of through the VPN, and says bypassing the VPN improves Teams quality. Your VPN vendor sets this up.
Step 4: Consider QoS (maybe)
Microsoft says a small business with few users might not need Quality of Service (QoS), but should consider it if it's seeing network delays. If you do set it up, Microsoft's recommended client source ports for audio are 50,000–50,019 with DSCP value 46 (Expedited Forwarding) (Implement QoS in Teams). Microsoft says QoS settings have to be applied consistently, on computers and devices, network switches, and routers to the internet, because any part of the path that doesn't support them can degrade calls. My view: in a small office, check for bandwidth hogs, the firewall, and the VPN before taking that on.
Step 5: Rule out the headset
- Microsoft says certified personal peripherals (headsets, speakerphones, webcams) are plug-and-play and offer call controls in Teams (Certified personal peripherals). Laptop speakers and microphones cause plenty of "they can't hear me" tickets. See Teams-certified headsets and desk phones.
- Check which microphone and speaker the user has selected in Teams' device settings, especially after docking or undocking a laptop.
- Wi-Fi: if Call Analytics shows Wi-Fi with poor signal for the bad calls, try a wired connection before anything else.
A quick checklist for every complaint
- When did it happen, and which number? Find the call in Users > Meetings & calls.
- Was the problem on our side or the other leg?
- Wi-Fi or wired? VPN on?
- Something else heavy running at that moment?
- Certified headset, or the laptop's built-in microphone?
More in the Teams Phone series: Calling Plan vs Operator Connect vs Direct Routing · Teams Phone licensing with Business Premium or E3 · Auto attendant and call queue setup · Port your business number to Teams · Teams-certified headsets and desk phones. Choosing a Microsoft 365 plan first? See Business Premium vs E3.
Sources
- Prepare your organization's network for Teams (Microsoft Learn)
- Use Call Analytics to troubleshoot poor call quality (Microsoft Learn)
- Set up Call Quality Dashboard (Microsoft Learn)
- Microsoft 365 URLs and IP address ranges (Microsoft Learn)
- Implement Quality of Service in Teams (Microsoft Learn)
- Certified personal peripherals for Teams (Microsoft Learn)
Useful links for this guide: Microsoft's network preparation guide and QoS guide. These are ordinary links, not affiliate links.