Choppy, delayed or dropped VoIP calls: how to find the cause before you blame the phones

Most choppy calls are a network problem, not a phone problem

When VoIP calls cut out, sound robotic, lag or drop, the cause is usually the network between your phones and the internet rather than the phones themselves: not enough upload capacity, too much jitter or packet loss, crowded Wi-Fi or an aging router. Less often it is a single headset, a computer, a firewall setting or the provider. You can narrow it down in an afternoon by noticing exactly what the bad calls sound like, testing your connection at the time the problems happen, and checking whether everyone is affected or only some people.

I am Beau Bearden, Channel Sales Manager at Cleod9 Voice, a business phone and unified communications company in Arlington. Call quality complaints are among the first things I hear from offices thinking about switching providers, and a surprising number of them follow the business to its next provider because the real cause was never found. This guide is how we work through it.

Put a name to what you are hearing

Different sounds point to different causes, so the first step is to describe the problem precisely. Ask the people who complain to tell you which of these they hear, and on which calls:

• Words drop out or voices turn metallic and robotic: usually packet loss or jitter, meaning pieces of the audio arrive late or not at all
• People keep talking over each other or there is a pause before replies: delay, also called latency
• One side cannot hear the other at all: often a router or firewall setting blocking audio in one direction
• Calls drop at about the same point every time: often a router or firewall timing out the connection
• Everything sounds fine early and falls apart at the same hour each day: the connection is congested by something else
• Only one person has trouble: their Wi-Fi, computer, headset or desk phone

The numbers that decide call quality

Speed is the number everyone checks, but it is rarely the one that matters most. Our own VoIP readiness guidance puts a single voice call at roughly 100 Kbps up and down, and an office of ten on calls only at about 1 Mbps each way. Most business connections have far more than that. What breaks calls is usually quality, not quantity.

The same guidance sets the targets we look for. Latency should stay under 150 milliseconds, in line with the ITU-T G.114 recommendation; between 150 and 250 milliseconds, callers start talking over each other. Jitter under 30 milliseconds is generally unnoticeable, and above that, audio can sound choppy even when the speed looks fine. Packet loss should stay under 1 percent for clear calls; between 1 and 3 percent you hear the occasional garbled word, and above 5 percent calls are often unusable. Video needs more room: the guidance lists about 1.5 Mbps each way for a one-to-one HD video call.

Upload deserves special attention. Many business plans are fast downstream and much thinner upstream, and every word your staff say travels up. That is why we recommend planning for at least double the minimum on upload. A quick way to see it for yourself is to run a speed test while someone uploads a large file; if ping and jitter jump, voice will suffer the same way.

Five checks you can run yourself this week

None of these requires a technician, and together they usually point clearly toward the cause:

• Run a speed test that reports ping and jitter, not just speed, from a wired computer, at the hour calls are worst, and again early in the morning
• Move one affected person from Wi-Fi to a network cable for a day and see whether their calls improve
• Look at what else uses the upload at the bad hour: cloud backups, file syncing, large email attachments, security cameras uploading video
• Try the same call on the mobile app over cellular data; if it is clear there, the problem is inside your office network
• Write down the time, the number and what was heard on every bad call for a week, so whoever investigates has evidence instead of impressions

When to stop testing and call your provider or IT firm

If the tests show high jitter or packet loss on a wired connection, the problem is in the router, the network equipment or the internet line itself, and that is work for whoever manages your network. If wired calls are clear but Wi-Fi calls are not, the wireless network needs attention. If everything tests clean and calls are still bad for everyone, bring your log to your phone provider, because the problem may be in their routing or your account configuration.

Call sooner if clients are complaining, if calls drop during conversations that matter, or if the problem started suddenly after a change such as a new router or internet plan. A sudden change usually has a specific cause that a technician can find quickly. Do not live with it for months; bad call quality quietly costs you clients who never mention why they stopped calling.

Why the trouble shows up at the same hour every day

Time-of-day problems almost always mean something is competing with voice for the same connection. A nightly backup that slipped into business hours, a staff member uploading large files, a video meeting on the conference room screen, or simply an office that has grown from eight people to twenty on the same internet plan. Voice packets are small but impatient; when the line is full, they arrive late or not at all, and that is exactly what jitter and packet loss sound like.

Wireless networks add their own version of this. Congested wireless channels and an outdated router add jitter before traffic even leaves the building. In a multi-tenant office building, dozens of neighboring networks can share the same airwaves, which is why one floor can have perfectly clear calls and another cannot.

When the bad calls come from people working at home

Remote staff add a network you do not control. A home connection shared with children streaming video, a router in a closet two rooms away, or a residential plan with a thin upload can make one person sound broken on every call while the office sounds fine. The same checks apply: a wired test at the hour calls are bad, a comparison with the mobile app on cellular data, and a look at what else in the house uses the connection.

Often the cheapest fix is a network cable from the router to the laptop, or moving the router closer to the desk. If someone's home connection cannot carry calls reliably, the mobile app on cellular data can be a better default for that person. For staff who work from home around Dallas only part of the week, it is worth agreeing on a simple rule: calls that matter happen on the wired connection or the office line.

What a proper fix looks like

The lasting fixes are usually unglamorous. A router that can prioritize voice traffic over everything else, often called quality of service, so a backup cannot crowd out a client call. Desk phones and front-desk computers on network cables instead of Wi-Fi. An internet plan with enough upload for the size the office has become. Backups and large syncs scheduled after hours. In offices with several locations, the same checks at every site, because one weak connection affects every call that touches it.

This is work we do alongside your IT provider rather than instead of them. If you do not have one, or your current firm takes days to respond, Anthony Omini's guide on what a small office actually needs from IT support is a good place to start. When we install a system, we look at the network first for exactly this reason; it is far easier to fix before go-live than after.

When it really is the phone, the headset or the provider

Sometimes the network is clean and the problem is closer to the person. A cheap or failing headset can produce crackle that sounds like a network fault. A computer running dozens of browser tabs and a video call at the same time can starve the softphone. A desk phone on old firmware may behave badly. Swapping the headset or trying the call from another device settles most of these in minutes.

If calls are bad everywhere, on every device, wired and wireless, and your connection tests clean, the provider has to look at its side. A good provider will ask for your call log and examine specific calls rather than tell you to restart the router. If you set the system up yourselves, it is also worth reviewing the configuration; my guide on setting up a cloud phone system yourself lists the settings that most often go wrong.

Keeping calls clear after the fix

Call quality drifts as offices change. New hires join, more people work from home, a security camera system starts uploading, the internet provider changes your equipment. Re-run the speed and jitter test whenever something like that happens, and put it on the list for your yearly phone system checkup. It takes ten minutes and catches problems before clients do.

Clear calls depend on the connection staying up, too. If your office in Dallas or anywhere in the metroplex loses internet during a storm, your calls should ring somewhere else rather than stop; my guide on keeping business phones answering through a power or internet outage covers how that is set up. If you would like a second set of eyes on your current call quality, we are glad to look at it with you and your IT provider.

Questions people ask me