Bad call quality comes down to network. Almost always. The phones are fine. The servers are fine. Something between your router and the internet is adding latency, dropping packets, or both.
Run one command, check one chart in the portal, and you will know where to look.
The first test
Open a command prompt on a computer at the affected location and run:
ping -t 5 8.8.8.8
This pings Google's DNS server every 5 seconds until you stop it. Let it run for a minute. Look at the times.
Consistent numbers under 50ms are healthy. 50 to 100ms is acceptable but noticeable on calls. Anything that regularly spikes above 100ms or jumps wildly from 20ms to 300ms indicates a network problem. That is where to focus.
Latency and jitter
Latency is how long a packet takes to reach the destination. Jitter is how much that time varies from packet to packet.
Voice can tolerate steady latency up to around 150ms. What it cannot tolerate is jitter. If ping times swing from 20ms to 200ms and back, your audio breaks up even when the average looks fine. The variation is the problem.
The fix is almost always on your network. Congestion, weak Wi-Fi signal, or an overloaded router.
Webex quality stats
Webex tracks its own quality metrics for every call. Open the Webex app, find the recent call, and click for call details. You will see packet loss, jitter, and round trip time reported by the Webex client directly.
If Webex reports high packet loss, the network is dropping audio packets before they reach us. If Webex reports low packet loss but the audio still sounds bad, the problem is upstream, at the carrier or the other party.
Upload matters more
Most people think of internet speed as download. For voice, upload matters more. Your voice has to go out to the internet. If your upload bandwidth is saturated (backup software running, cloud sync uploading large files, someone streaming to Twitch), calls degrade.
Aim for at least 100 Kbps upload per concurrent call, with headroom. A 10-line office making 4 simultaneous calls needs 400 Kbps just for voice, plus whatever else is happening on the network.
Filters and firewalls
Content filters, SD-WAN appliances, and aggressive firewalls sometimes interfere with Webex traffic. Signs include one-way audio, calls that connect but have no voice, or calls that drop after a few seconds.
If you suspect a filter, test Webex from a device outside the filtered network (a cell phone on 5G works). If it sounds fine off-network but bad on-network, the filter is the problem. Your IT team can whitelist Webex traffic or allow the specific ports.
Mobile cellular quality
When the Webex mobile app sounds bad, it is almost always the cellular signal. Cellular quality depends entirely on your carrier in that building. A weak LTE signal makes calls garbled no matter what we do.
If cellular is unreliable where you work, use Wi-Fi calling through the Webex app or turn on BroadWorks Anywhere so the system can ring your native cell number as a fallback.
Getting help
Run the ping test, open the Webex quality stats, and call 718.395.1550. Share what you saw. We can usually narrow the cause in a few minutes once we know which layer is failing.