Glossary
What is a VoIP number?
A VoIP number is a phone number that runs over the internet instead of a SIM card or a copper line. It looks like any other number, so the only way to spot one on a lead list is a line type lookup.
The terms behind a VoIP number
| VoIP | Voice over Internet Protocol. Calls are carried as data over an internet connection instead of over a mobile radio network or a traditional copper phone line. |
| Fixed VoIP | A VoIP line tied to a physical service address, such as home phone service from a cable or internet provider. It works like a landline from the caller's side. |
| Non-fixed VoIP | A VoIP number that is not tied to an address and can be used from any internet connection, such as numbers from calling and texting apps or cloud phone systems. |
| Line type | The kind of line a number is: mobile, landline, VoIP or toll-free. A line type lookup is how you tell a VoIP number apart from a cell phone. |
| Carrier | The company that currently holds the number. For VoIP numbers this is often a wholesale carrier or communications platform rather than a consumer brand. |
Where VoIP numbers come from
- Calling and texting apps such as Google Voice and TextNow.
- Cloud business phone systems such as RingCentral and Vonage.
- Developer platforms that rent numbers to apps and businesses, such as Twilio, Telnyx and Bandwidth.
- Internet home phone service bundled by cable and internet providers (fixed VoIP).
VoIP number vs. cell phone number
| VoIP number | Cell phone number | |
|---|---|---|
| Runs on | An internet connection | A mobile network and a SIM card |
| Tied to a device | No. The same number can ring an app, a desk phone or a browser | Yes, the phone holding the SIM (or eSIM) |
| Typical sources | Calling and texting apps, cloud business phone systems, internet home phone service | Wireless carriers and the prepaid brands that run on them |
| Who usually answers | Depends: a person, a business phone tree, or nobody if the app is no longer used | The person carrying the phone |
Why VoIP numbers matter on a lead list
- Texting: some VoIP numbers cannot receive SMS, so an SMS campaign may want them flagged first.
- Who picks up: a VoIP number on a consumer form may be a business line or an app the person no longer uses.
- Not a compliance check: knowing a number is VoIP says nothing about Do Not Call status or consent.
What TrueSearch returns, and does not
| Valid or dead (disconnected / not assigned) | Yes, every number |
| Line type: mobile, landline, VoIP, toll-free | Yes, every number |
| Carrier name | Yes, every number |
| Bulk upload (CSV or Excel) | Yes, results in about 30 seconds per 1,000 numbers |
| REST API | Yes (JSON, one API key) |
| Claude / ChatGPT / Cursor connector (MCP) | Yes |
| National or state Do Not Call check | No, not yet |
| Known TCPA litigator check | No, not yet |
| FCC Reassigned Numbers Database check | No |
| Starting price | $97/month for 5,000 numbers, 7-day free trial |
| One-off list | $20 per 1,000 numbers, no subscription |
Upload a CSV or Excel file. Every number comes back valid or dead, mobile, landline, VoIP or toll-free, with carrier.
Starter: $97/month for 5,000 numbers after the 7-day trial. Cancel anytime.
Questions
What is a VoIP number?
A VoIP number is a phone number whose calls run over the internet (Voice over Internet Protocol) instead of a mobile network or a copper landline. It looks like any other 10-digit US number; you can only tell it is VoIP with a line type lookup.
What is the difference between fixed and non-fixed VoIP?
Fixed VoIP is tied to a physical service address, like internet-based home phone service. Non-fixed VoIP is not tied to an address and works anywhere there is an internet connection, like numbers from calling apps or cloud phone systems.
Can a VoIP number receive text messages?
Many can, depending on the provider and how the number is set up. Some VoIP numbers cannot receive texts at all, so a VoIP result on a lead list is worth deciding on before an SMS campaign.
How can I tell if a number is VoIP?
You cannot tell from the digits alone. Run a line type lookup: it returns mobile, landline, VoIP or toll-free plus the carrier. TrueSearch has a free single-number carrier lookup and bulk CSV checks on paid plans.
Are Google Voice and TextNow numbers VoIP?
Yes. Google Voice and TextNow numbers are VoIP lines, not tied to a SIM card. Depending on the data, the carrier may show the app or a wholesale provider.
Should I remove VoIP numbers from my lead list?
It depends on your campaign. Some teams keep them for calling and drop them for texting; others drop them entirely. TrueSearch flags them so you can decide; it does not remove anything on its own.
Does TrueSearch check Do Not Call status?
No. TrueSearch checks validity, line type and carrier only. For Do Not Call status, use the National Do Not Call Registry at donotcall.gov.
Related: what is phone line type?, what is an HLR lookup?, free carrier lookup, VoIP number detection and landline checker.
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This guide is general information, not legal advice. TrueSearch for Business checks validity, line type and carrier from licensed telecom data. It does not check the National Do Not Call Registry, state DNC lists or the FCC Reassigned Numbers Database. Not a consumer reporting agency; not for FCRA purposes.