Core Concepts
VoIP (Voice over Internet Protocol)
By Myroslav Orshak · operates licensed carrier infrastructure · Updated September 2026
VoIP (Voice over Internet Protocol) is a technology that converts speech into digital data packets and transmits phone calls over the internet instead of over traditional copper telephone lines.
How it works
When you speak into a VoIP phone or app, software called a codec (the common ones are named G.711 and Opus) turns your voice into digital data. That data is chopped into tiny packets — each carrying about 20 milliseconds of sound — and sent over your internet connection.
A second standard called SIP handles the mechanics of the call: it tells the network your phone is online, rings the other party, and hangs up cleanly when you're done. The voice packets themselves are reassembled back into sound at the other end within milliseconds, so the conversation feels instant.
Calls to ordinary phone numbers don't stay on the internet the whole way. Your provider hands them off to the regular phone network (the PSTN). That is why a VoIP line can call any landline or cell phone, and receive calls from them.
Why it matters
The economics are the headline. A VoIP line has no copper loop to maintain, so business plans cost a fraction of traditional lines. And features that used to be add-ons, such as the auto attendant, voicemail-to-email, call recording, and mobile apps, are included. The same number works on a desk phone, a laptop, and a mobile app, wherever there's internet.
The switch is also becoming mandatory. US carriers are actively retiring the copper network with FCC approval, and prices on remaining POTS lines have climbed steeply as a result. For most businesses the question is no longer whether to move to VoIP, but which provider to move to.
Toll-quality VoIP targets a Mean Opinion Score (MOS) of 4.0 or higher — the G.711 codec used by most business providers tops out at 4.4 — and the ITU recommends keeping one-way latency under 150 ms for natural conversation.
Related terms
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See the best business phone systems →Frequently asked questions
Do I need special equipment to use VoIP?
No. A softphone app on your computer or smartphone is a complete VoIP endpoint. Offices that want desk phones use IP phones that plug into the network, and existing analog phones can be kept in service with an inexpensive adapter (an ATA). The only hard requirement is a decent internet connection.
Can I keep my phone number when switching to VoIP?
Yes. FCC rules give you the right to port your number to any provider serving your area, and the losing carrier can't refuse a valid request. Simple single-number ports often complete in a few business days; multi-line business ports typically take a few weeks.
Does VoIP work if the internet goes down?
Your desk phone won't, but your number keeps working: cloud VoIP platforms fail over to mobile apps or forward to any number you choose, so calls still reach you on a phone with cellular data. That's a resilience model copper can't match — but it does mean you should register your E911 address and keep a cell phone fallback configured.
How much bandwidth does a VoIP call use?
Very little — about 100 kbps per call, so ten simultaneous calls fit comfortably in 1 Mbps, a fraction of any modern business connection. Speed is almost never the problem; brief data hiccups (packet loss) and uneven timing (jitter) are what actually make calls sound bad.