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Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

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Speed and call quality test

Check your connection for phone calls: delay, jitter and dropped packets, plus speed, live as it runs. Leave the monitor running to catch problems that come and go.

Compare with other test servers

These providers see your IP address while they test. M-Lab publishes every result, with your IP address, in its open research data (M-Lab privacy policy).

What the numbers mean for calls
Delay (latency)
How long a round trip to the phone system (or our server) takes. Under 50 ms is good for calls; over 150 ms you start to talk over each other.
Jitter
How much the delay varies from one moment to the next. Phones smooth out up to about 30 ms; more than that causes choppy or robotic audio.
Packet loss
Requests that didn't come back in time. Even 1 % causes gaps in speech.
Delay when busy
Extra delay while someone uploads or downloads (often called bufferbloat). A big rise means calls break up whenever the line is busy; a router with SQM or QoS usually fixes it.
Other test servers
Each provider's servers sit in a different place, so speeds vary a little between them. If all of them are slow, the line is the bottleneck; if one stands out, it's that server or the route to it.
More than one line
Some routers (DrayTek and Ubiquiti, for example) share traffic across two or more broadband lines. Each line has its own public address. The test finds them, shows each line's share of the speed and the combined total, and warns if calls could switch between lines, which causes one-way audio and dropped calls.
Call score (MOS)
An estimate of call quality from 1 to 5, worked out from the figures above using the ITU-T E-model. 4.0 and above is as good as a landline.

For the continuous monitor, keep this tab open and visible, and the computer awake: browsers slow down hidden tabs, so readings taken while the tab is hidden are left out and shown as "Not measured". Leaving the page stops the monitor.

Phone calls use UDP; this browser test uses HTTPS, so lost packets show up as delay spikes rather than gaps. It is a close guide, not a replacement for a test from the phone system itself.

About this tool

Most speed tests only report download speed. Phone and Teams calls fail for other reasons: delay (latency), uneven delay (jitter) and lost packets. This test measures all three, gives an estimated call quality score from 1 to 5, then measures download and upload speed and how much delay rises while the line is busy (bufferbloat).

If your router shares traffic across two or more broadband lines, the test finds each public address and shows each line's speed and the combined speed. You can also compare the result with other providers' test servers in the same run, to tell a slow line from a slow server.

Common questions

What is a good result for phone calls?

The test grades delay of 50 ms or less, jitter of 10 ms or less and packet loss of 0.5 % or less as good. A call quality score of 4 or more out of 5 is good; below 3.6 most people notice problems.

Why is my speed lower than my broadband package?

Wi-Fi, other devices using the line and the test server all reduce the result. For the truest figure, test on a cabled computer with nothing else running, and compare with the other test servers.

What is bufferbloat?

When the line is full, some routers queue too much data and every packet waits. Calls break up whenever someone downloads or uploads. The test shows how much the delay rises under load.

Does the test record my results?

No. Results stay in your browser. The optional M-Lab server publishes its results with your IP address, so it is off unless you tick it.