VoIP (Voice over Internet Protocol) is a way of making phone calls over an internet connection instead of a traditional phone line. Your voice is turned into small packets of data, sent across the network, and turned back into sound at the other end. So what is VoIP for a business owner, in practice? It is the technology under nearly every modern business phone system: desk phones that plug into your network, an app that makes your mobile ring like your office extension, and a phone system that can live in the cloud instead of a closet.
Your customers cannot tell the difference. They dial your number, it rings, someone answers. What changes is what sits behind that call, what it costs, and where your staff can take it from.
How VoIP works
A traditional phone line (often called POTS, for plain old telephone service) is analog. Your voice becomes a continuous electrical signal that travels over copper wire to the carrier's central office, which switches it to the person you called.
VoIP does the same job digitally:
- Your phone or app turns your voice into data. The sound is sampled, compressed, and cut into small packets. On a typical call that is about fifty packets a second, each carrying around twenty milliseconds of audio.
- A signaling protocol sets up the call. Most business VoIP uses SIP (Session Initiation Protocol), the standard for creating, changing, and ending calls. It handles the "ring this number," "they answered," and "hang up" parts.
- The packets cross the network. Voice travels as a steady stream using the Real-time Transport Protocol (RTP).
- The far end turns them back into sound. If the other person is on a mobile or a landline, your provider hands the call to the public telephone network for the last leg.
Behind the phones there is usually a PBX (private branch exchange): the system that routes calls between extensions and runs your auto attendant, ring groups, and voicemail. With VoIP, that PBX is software, and it can run in a provider's data center or on a server in your office.
What a business needs for VoIP
- An internet connection that carries clean voice. Less bandwidth than you would guess: a single call uses a fraction of what one video stream does. Quality matters far more than speed (more on that below).
- Something to talk on. IP desk phones, cordless DECT handsets, a softphone on your computer, or the mobile app. Most offices mix all four. We deploy Yealink desk phones and headsets, configured before they arrive.
- A phone system and a provider. Either a hosted system, a system you own connected to SIP trunks, or a hybrid of the two.
- Your phone numbers. Business numbers are portable, so you can keep the numbers your customers already know.
Three ways businesses use VoIP
Hosted VoIP (hosted PBX). The provider runs the phone system in its data centers and you plug phones into your network. Nothing to buy up front beyond phones, nothing to maintain. This is what most small and mid-sized businesses choose, and it is what our hosted business phone systems are.
An on-premise VoIP phone system. The same software runs on a server in your building, which suits large campuses and organizations with strict requirements. We compare the two in on-premise PBX vs cloud hosted PBX.
SIP trunking. If you already own a modern phone system, you can keep it and replace only the lines behind it with internet-delivered trunks. Our SIP trunking 101 guide explains how that works.
Why businesses switch to VoIP
Your phone goes where your people go
A traditional line is tied to a socket on the wall. A VoIP extension is tied to a person. Staff can take calls on their desk phone, their computer, or the mobile app for iPhone and Android, and calls can ring several devices at once or follow someone to their cell phone. For teams that work from home part of the week, this is usually the reason that matters most.
Features that used to cost extra come with the system
- Auto attendants (a digital receptionist), ring groups, and call queues that route callers to the right person
- Individual voicemail with transcription, delivered to email
- Text messaging (SMS and MMS), plus Facebook Messenger and WhatsApp
- Call recording and reporting on call volume and team performance
- Integration with CRM, Google Workspace, and Office 365
- Video conferencing and chat on the same platform as your calls
Costs that make sense as you grow
You stop paying for a separate line for every phone. Carriers still selling analog lines have made them steadily more expensive to keep. Pricing models differ between providers, and the one worth watching is per-user billing, which grows with every hire. We price by call capacity instead: you pay for the calls your business carries at its busiest moment, and adding a phone for a new hire or a meeting room does not add a per-seat fee.
Easy to change
Adding a user, a new location, or a holiday schedule is a configuration change rather than a technician visit. An office move means unplugging phones in one building and plugging them in at the next.
What VoIP depends on (the honest part)
Internet quality, not internet speed
A voice call is a small, steady stream of packets. It does not need much bandwidth, but it cannot tolerate packets that arrive late, out of order, or not at all. That is why a connection can pass a speed test and still produce choppy calls: a speed test measures throughput, and packet loss and jitter are what ruin a call.
The easiest way to know where you stand is to test it. Our free call quality test at voiptest.com runs in your browser in about a minute, with no account and no microphone permission. It sends a real voice stream over your connection and scores what a caller would have heard, using the same standards-based method carriers use. We explain how it works in our voiptest.com launch post.
Power
As the FCC has noted, a traditional copper landline typically keeps working in a power outage because the line carries its own power, while IP-based phone service usually needs a separate power source. In an office, desk phones usually draw power from the network switch, so when the building loses power, the desk phones go dark with it. With a hosted system the phone system itself is not in the building, so it keeps answering, and calls can fail over to mobile apps and cell phones until the power returns.
911
Because a VoIP phone can be plugged in anywhere, the address it reports for 911 has to be set deliberately. Kari's Law requires that anyone can dial 911 directly from a business phone system, and RAY BAUM'S Act requires the call to carry a dispatchable location. A good provider sets a 911 address for every location you have. Our post on Kari's Law and RAY BAUM'S Act covers what that means for your business.
Common questions about VoIP
Can I keep my business phone number?
Yes. Business numbers are portable between providers. The provider you move to should handle the porting paperwork and time the cutover so your published numbers keep working.
Do I need new phones?
Not always. Existing IP phones and SIP devices can often be reused, and the mobile app needs no hardware at all. Older analog handsets, and analog devices such as fire panels and elevator lines, need a closer look, which is part of any good assessment.
Is VoIP the same as a cloud phone system?
VoIP is the technology. A cloud (hosted) phone system is one way of using it, where the provider runs the system for you. An on-premise system and SIP trunking use VoIP too.
Getting started
Run the call quality test from your office, list the numbers and phones you have today, and decide how much of the system you want to own. If you would rather someone else handled it, our hosted VoIP phone systems are built, hosted, and supported by US-based engineers, priced by capacity, with no long-term contract. To see every option side by side, start with our business phone systems overview.