On this page
- How a VoIP call works
- What you need to use VoIP
- Do you need a special handset for VoIP?
- Interconnected VoIP vs app-to-app calling
- Can you use a VoIP phone without a provider?
- VoIP phone numbers and porting
- 911 on VoIP
- Business VoIP vs residential VoIP
- What business VoIP costs
- Common VoIP call quality problems
- Frequently asked questions
How a VoIP call works
VoIP stands for voice over internet protocol. Instead of sending your voice down a dedicated copper phone line, a VoIP phone or app turns it into small data packets and sends them over your internet connection. Your provider then connects the call to the regular phone network, so you can reach any phone number and anyone can dial yours.
- You speak into an app, a desk phone or an adapter. The device converts your voice to digital audio using a codec. Zoom Phone, for example, uses the Opus codec, which adjusts to the bandwidth available (Zoom).
- The audio travels over your internet connection to your VoIP provider's servers, the same way any other internet traffic does.
- The provider routes the call. Calls to another user on the same system stay on the provider's network; calls to outside numbers are handed to the public phone network.
- Incoming calls reverse the trip. Someone dials your number, the provider receives the call and rings your apps and desk phones at once, or follows the routing rules you set (a phone menu, a ring group, voicemail).
What you need to use VoIP
An internet connection
Dialpad asks for at least 100 Kbps up and down per simultaneous voice call, and for best quality latency under 125 ms, jitter under 40 ms and packet loss under 2% (Dialpad). Zoom estimates 60 to 100 Kbps per call (Zoom). Ten calls at once at Dialpad's minimum is about 1 Mbps each way.
A device
An app on your cell phone or computer (a softphone), an IP desk phone, or a regular analog phone plugged into an adapter (ATA). Every system we compare has mobile apps, and most have desktop apps.
A provider and a number
The provider gives you a local or toll-free number, connects you to the phone network and provides 911 service. You can usually port the number you already have.
Router settings
Dialpad recommends turning off SIP ALG, deep packet inspection and stateful packet inspection for its traffic, and for mobile calls at least 4G or equivalent Wi-Fi.
Do you need a special handset for VoIP?
No. The simplest setup is the provider's app on the phones and computers you already own. If you want desk phones, you have two options:
- IP desk phones that connect to your network. Zoom sells Mitel, Yealink and Poly phones and lists zero-touch provisioning; Ooma sells its own IP phones; Nextiva says it works with any desk phone and bills phones per unit.
- An analog telephone adapter (ATA) lets an ordinary phone use VoIP. Google Voice's paid plans list "desk phone and ATA support", and Zoom Phone lists analog device support.
Some app-based systems do not support desk phones at all: Grasshopper says it needs "no desk phone or additional device", and Quo's pages do not mention desk phones.
Interconnected VoIP vs app-to-app calling
The FCC uses the term interconnected VoIP for services that can call and receive calls from regular phone numbers (FCC). That is what every business phone system on this site is. App-to-app calling is narrower: Microsoft Teams Free gives free video calls and chat but no phone number, and Talkatone offers unlimited free calls between Talkatone users anywhere. Those are useful for internal calls, not as a business line customers can dial.
Can you use a VoIP phone without a provider?
Only for calls inside your own network or app. A VoIP desk phone can call another VoIP phone directly, and apps like Teams Free connect their own users for free. But reaching regular phone numbers, and having a number customers can dial, requires a provider connected to the public phone network. That provider also supplies 911 service, which the FCC requires interconnected VoIP providers to offer.
VoIP phone numbers and porting
A VoIP number looks like any other phone number: local with a familiar area code, or toll-free. The FCC says number porting "can be done between wireline, IP and wireless providers," and simple ports should finish in one business day (FCC). Keep the old service running until the new provider confirms the port. More on virtual phone numbers and toll-free numbers.
911 on VoIP
Because a VoIP phone can work from almost any internet connection, the FCC says a 911 call may reach the call center without automatically sending your number or location. Its rules require interconnected VoIP providers to:
- provide 911 service to all customers as a standard feature,
- get your physical location before service starts,
- get your acknowledgement that you understand the limits, and
- give you warning labels where 911 may be limited.
It also warns that VoIP "may not work during a power outage or when the internet connection fails or becomes overloaded," and suggests backup power or a cell phone as backup (FCC). Multi-line systems must also let staff dial 911 without a prefix and notify a central point when they do (Kari's Law, since February 16, 2020; FCC).
Business VoIP vs residential VoIP
Home VoIP services such as Ooma's Basic home phone are priced for households and can restrict business use: Ooma's residential terms let it end service used in a way "inconsistent with residential, non-commercial use." Business VoIP adds what companies need: several users and extensions, phone menus, ring groups, call recording, business texting registration and admin controls.
What business VoIP costs
Entry plans run $10 to $30 a user a month at list price. Monthly cost for 5 users on each company's lowest plan, billed annually where offered:
Full figures for 1 to 25 users are on the pricing page, and the phone system comparison shows which plan includes which features.
Common VoIP call quality problems
- Choppy or robotic audio usually means jitter or packet loss. Dialpad treats jitter under 100 ms and loss under 5% as acceptable, and under 40 ms and 2% as optimal.
- Delay or people talking over each other points to latency; Dialpad's acceptable limit is 200 ms round trip.
- One-way audio or dropped calls can come from router features that rewrite VoIP traffic, which is why Dialpad asks you to turn off SIP ALG.
- No service in an outage: keep a charged cell phone, or put your modem and router on backup power, as the FCC suggests.
Frequently asked questions
What is VoIP in simple terms?
Phone calls carried over the internet instead of a copper phone line. A VoIP provider gives you a phone number that rings in apps and on desk phones and connects your calls to regular phones.
Do you need a special handset for VoIP?
No. You can use the provider's app on a cell phone or computer. For desk phones, use IP phones the provider supports, or plug a regular phone into an adapter (ATA) where the provider supports it, as Google Voice's paid plans and Zoom Phone do.
Can I use a VoIP phone without a provider?
Only for calls within your own network or between users of the same app. Calling regular phone numbers and getting a number people can dial needs a provider connected to the public phone network.
How much internet speed do I need for VoIP?
Dialpad asks for at least 100 Kbps up and down per simultaneous call, and Zoom estimates 60 to 100 Kbps. Stability matters as much as speed: Dialpad's targets are latency under 125 ms, jitter under 40 ms and packet loss under 2%.
Does VoIP work in a power outage?
Not unless your internet equipment has power and a connection. The FCC warns VoIP may not work during a power outage or internet failure and suggests backup power or a cell phone as backup.
Can I keep my phone number if I switch to VoIP?
Usually yes. The FCC says porting works between wireline, IP and wireless providers when you stay in the same area, and your old company cannot refuse because you owe money.
What is the best cloud-based calling software for businesses?
It depends on the job. On published prices: Dialpad ($15 a user billed annually) for AI transcripts on the entry plan, Zoom Phone ($16) for auto attendants and desk phones on every plan, Quo ($15) for texting, and Google Voice ($10) if you already use Google Workspace.