VoIP stands for Voice over Internet Protocol. Rather than reserving a dedicated circuit through a telephone network, a VoIP call converts speech into data packets and sends them across the internet like any other traffic. The person on the other end usually cannot tell the difference.
What changes is not the call quality but the economics. A traditional phone line is tied to physical infrastructure and an account relationship with a carrier. A VoIP number is a software record. It can be issued instantly, in bulk, and abandoned without consequence.
Why VoIP shows up as its own line type
When a lookup reports a number as VoIP, it is reading the routing records that tell the phone network where to send a call. Those records identify the operator responsible for the number, and VoIP providers are identifiable in that data.
This is why a lookup is the only reliable detection method. VoIP numbers are allocated from the ordinary North American numbering plan, so there is no prefix pattern to match on and no area code that means "internet number". Any tool claiming to detect VoIP from the number alone is guessing.
Fixed vs non-fixed
Fixed VoIP is bound to a verified service address — cable and fibre home phone service, most business phone systems. It behaves like a landline and carries similar trust.
Non-fixed VoIP needs no address. It is obtainable in minutes, often free, and can be discarded the same day. This is the category that correlates with fraud and with lead lists padded to hit a row count.
What a high VoIP share tells you about a list
A purchased consumer lead list with a large proportion of VoIP numbers is telling you something about how it was assembled. Legitimate consumer leads are dominated by mobile numbers, because that is what people give out. A file heavy with non-fixed VoIP usually means one of three things: the leads are old and have been resold repeatedly, the source accepted throwaway numbers on its forms, or the row count was inflated.
Treat the VoIP percentage as a quality metric for the vendor, not just a filter for the file. It is one of the few signals available before you spend anything dialling.
The compliance position is genuinely unsettled
The TCPA restricts autodialed and prerecorded calls to numbers assigned to cellular and similar services, and to "any service for which the called party is charged for the call". Whether a given VoIP number falls inside that language has been litigated repeatedly and does not have one clean answer — outcomes have turned on how the specific service is billed and provisioned.
We are not going to tell you VoIP is safe to autodial, because that is not established. The defensible operating assumption is that a VoIP number may attract the same restrictions as a mobile, and that consent and litigator screening should be handled the same way for both. Where the exposure is material, this is a question for counsel rather than for a vendor page.
Checking line type before you dial
NumberBroom reports VoIP as a distinct line type on every row, alongside mobile, landline, toll-free and disconnected, so you can segment rather than guess. The same pass runs the litigator check. Check a single number free, or see bulk pricing.
Frequently asked questions
Can you tell if a number is VoIP just by looking at it?
No. VoIP numbers are drawn from the same numbering plan as every other US number, so there is no reserved area code or prefix that marks one. The only reliable method is a lookup against carrier routing data, which reports the line type directly.
What is the difference between fixed and non-fixed VoIP?
Fixed VoIP is tied to a verified physical address — typically cable or fibre telephone service. Non-fixed VoIP requires no address verification and can be obtained in minutes with an email address, which is the category that includes most app-based services.
The distinction matters for risk scoring: non-fixed VoIP is trivially disposable, so it appears disproportionately in fraudulent signups and low-quality purchased lists. Fixed VoIP behaves much more like a landline.
Can VoIP numbers receive SMS?
Some can and some cannot, which makes VoIP the least predictable line type for messaging. Many app-based services support SMS; many business VoIP lines do not, and messages to them fail without a useful error. If SMS delivery matters to your campaign, treat unverified VoIP as unreliable rather than assuming either way.
Should I remove VoIP numbers from my calling list?
It depends on what you sell. For consumer outbound where the goal is reaching an individual on a personal line, VoIP is usually worth removing — the connect rate is poor and the fraud correlation is real. For B2B, VoIP is often a legitimate business phone system, and stripping it would delete good prospects.
The useful move is to segment rather than delete: flag the line type, then decide per campaign.