What Is a Fixed VoIP Number?
A fixed VoIP number is a VoIP number associated with a physical service at a specific address. The classic example is a home phone line from a cable or fibre company: the calls run over the internet, but the service is installed at one address and the number is registered to it.
Line-type lookup services describe a fixed VoIP number as a virtual number associated with a physical device or service location, as opposed to one obtained online. Because the service is anchored to a place, fixed VoIP numbers behave much like landlines in the eyes of carriers, banks, and emergency services.
Typical features of fixed VoIP numbers:
- Tied to a service address: The number is provided at, and registered to, a known location.
- Verified customer: The provider knows who the account holder is and where the service is installed.
- Emergency location: 911 (or 999/112) calls can be matched to the registered address automatically.
- Wider acceptance: Fixed numbers are less likely to be rejected for security codes.
What Is a Non-Fixed VoIP Number?
A non-fixed VoIP number is a VoIP number obtained online without being tied to a physical address or device. You sign up, choose a number, and use it on any phone, computer, or app, anywhere with internet. It's also called nomadic VoIP.
Non-fixed numbers are what free calling apps and many online number services provide, and many business providers issue them too. They're legitimate, carrier-issued numbers that work normally for calls and texts. The difference is how services classify them, and what that means for trust.
Typical features of non-fixed VoIP numbers:
- Location-independent: Use the number from any country, on any device.
- Fast to set up: Often live within minutes, with light or no verification.
- Easy to scale: Add numbers in other cities or countries without an office there.
- Lower trust in fraud checks: Because they can be created quickly, some services treat them as higher risk.
Fixed vs. Non-Fixed VoIP: Key Differences
The main difference is whether the number is anchored to a physical location. That one difference affects verification, trust, and emergency calling.
| # | Fixed VoIP number | Non-fixed VoIP number |
|---|---|---|
| Tied to | A physical service address | An online account; no fixed address |
| Where it can be used | Mainly at the registered location | Anywhere with internet |
| Setup | Usually slower; address and identity checks | Often minutes |
| Line-type lookup result | Fixed VoIP | Non-fixed VoIP |
| Security codes (banks, apps) | Generally accepted | Often refused |
| Spam-risk scoring | Usually treated as lower risk | More likely to be scrutinised |
| Emergency calls (US) | Automated dispatchable location required | Automated location if feasible; otherwise a registered address the user must keep current |
| Typical examples | Cable or fibre home phone; office VoIP lines at a fixed site | Free calling apps; many online and virtual number services |
| Best for | Businesses at one site that need maximum acceptance | Remote teams, travel, and presence in several markets |
How Services Tell Fixed and Non-Fixed Numbers Apart
Services tell the two apart with a line-type lookup. When you enter a number on a sign-up form, the service checks it against numbering and carrier databases, which return the line type (landline, mobile, fixed VoIP, non-fixed VoIP, or toll-free) and the carrier that holds it.
The classification comes from the carrier of record and how the number was issued, not from anything you set. That's why changing apps, devices, or settings doesn't help, and why the same number can be accepted by one service and refused by another: each service decides which line types it will allow. You can check your own number with a VoIP number lookup before you rely on it.
Why Some Services Reject Non-Fixed VoIP Numbers
Some services reject non-fixed VoIP numbers because those numbers can be obtained quickly and in bulk, which makes them attractive for fake accounts and fraud. Blocking the whole category is a blunt but simple defence.
The services most likely to refuse them are:
- Banks and fintech apps: For two-factor authentication and account recovery codes.
- Messaging apps: Some restrict registration with VoIP numbers.
- Marketplaces and social platforms: To limit fake and duplicate accounts.
- Government and tax portals: For identity verification.
If a service refuses your number, try its voice-call verification option if it has one. Use a mobile number for accounts that matter most, or use a number from a business provider that verifies its customers. For specific platforms, see how to get a virtual number for verification.
Emergency Calls: Fixed vs. Non-Fixed VoIP
Emergency calling is where the difference between fixed and non-fixed VoIP matters most, because emergency services need to know where you are.
In the US, the FCC's rules under RAY BAUM's Act require providers to send a "dispatchable location" (a street address plus details such as floor or suite) with 911 calls. The rules differ by type:
- Fixed VoIP: Since January 2021, providers must send the dispatchable location automatically with every 911 call.
- Non-fixed (nomadic) VoIP: Since January 2022, providers must send it automatically where technically feasible. Otherwise they may use the registered address (which the user must keep up to date), alternative location information, or, as a last resort, route the call to a national emergency centre.
In practice, if you use a non-fixed number, keep the emergency address on your account current, especially when you travel or work from different places. For emergencies, your mobile phone's regular dialler is the most reliable option, because the carrier sends your location automatically.
Benefits of Non-Fixed VoIP
Non-fixed VoIP has real advantages, which is why so many businesses and individuals use it despite the verification drawbacks.
Work from anywhere The number rings on your app wherever you are, which suits remote teams, travellers, and VoIP for remote working.
Local presence without an office Hold numbers in other cities or countries so customers can call you at local rates. Virtual phone numbers make this possible.
Fast setup and scaling Add numbers and users in minutes for a new market, a campaign, or seasonal staff.
Lower cost No installation or line rental, and fewer location-based charges.
Easy integration Numbers work with apps and business tools such as CRMs, shared inboxes, and call analytics.
Which Should You Use?
The right choice depends on what the number is for. Many businesses use both: a fixed or mobile number where acceptance matters most, and non-fixed numbers where flexibility matters more.
Choose a fixed VoIP number (or a mobile number) if:
- You need the number for bank, payment, or government verification.
- You run from one office and want the highest trust with carriers and customers.
- Reliable, automatic emergency location at a site is essential, such as in healthcare or a busy office.
A non-fixed VoIP number works well if:
- Your team is remote, hybrid, or often travelling.
- You want local numbers in several cities or countries.
- The number is for customer calls and texts, not for receiving security codes.
- You need numbers quickly for a launch, campaign, or new market.
Best Practices for Using a Non-Fixed VoIP Number
A non-fixed number can still be trusted by customers and carriers if you set it up well.
Use a provider that verifies customers Providers that know their customers can sign calls with strong caller-ID authentication (STIR/SHAKEN), which carriers trust more.
Set a clear caller ID Show your business name, and register it with the carrier analytics services to avoid "Spam Likely" labels. A custom caller ID helps callers recognise you.
Prefer local numbers Customers answer familiar area codes more readily than unknown ones.
Register for business texting In the US, texting from a local number requires A2P 10DLC registration, and toll-free numbers need toll-free verification.
Ramp up outbound calls gradually A new number that suddenly makes hundreds of calls looks like a robocaller.
Keep your emergency address current And make sure staff know to use their mobile dialler for emergencies.
Secure the account Use strong passwords and two-factor login, and limit international calling if you don't need it.
Next step
Choose the Number That Fits the Job
Fixed and non-fixed VoIP numbers both carry calls and texts perfectly well. The difference is how much services trust them and where they can be used. Use a fixed or mobile number for accounts that demand verification, and non-fixed numbers where flexibility and reach matter more.
If you'd like to try it, every Calilio plan includes a free US, Canada, or UK local number and a monthly bundle of free minutes and SMS.
Frequently Asked Questions
Short answers to the questions people ask most about fixed and non-fixed VoIP numbers.
What is the difference between fixed and non-fixed VoIP?
A fixed VoIP number is tied to a physical service at a known address; a non-fixed number is obtained online and can be used anywhere. Services check which type a number is and treat non-fixed numbers as higher risk.
Can a non-fixed VoIP number be traced?
Yes. It's registered to a provider and an account, so law enforcement can trace it through the provider with legal process. A public lookup shows the line type and provider, not the owner.
Can you text a non-fixed VoIP number?
Yes. Most non-fixed VoIP numbers can send and receive texts, though some short-code and verification messages may not be delivered to them.
Why won't my bank accept my VoIP number?
Many banks block non-fixed VoIP numbers for security codes because they can be created quickly online. Use a mobile number, or ask whether the bank offers voice-call or app-based verification.
Is Google Voice fixed or non-fixed VoIP?
Line-type lookup services give Google Voice as an example of a non-fixed VoIP number, which is why some services refuse it for verification.
Who uses non-fixed VoIP numbers?
Remote and distributed teams, startups, freelancers, frequent travellers, and businesses that want local numbers in several countries. Individuals also use them as a second number for online selling, dating, or privacy.
Can you call back a non-fixed VoIP number?
Yes. A non-fixed VoIP number is a normal, dialable phone number. Calling it back rings the owner's app or forwarding destination, wherever they are.
Is a VoIP number the same as a non-VoIP number?
No. A non-VoIP number is a traditional landline or a mobile number on a SIM card. Some verification services specifically ask for "non-VoIP" numbers because they are harder to create in bulk.
Can I change my number from non-fixed to fixed?
Not by changing settings. The classification comes from how the number was issued. You'd need a number from a service that is provided at a fixed location, or you can port the number to such a service, where the carrier of record changes.