How to Check if a Phone Number Is VoIP (and Why It Matters)

To check whether a phone number is VoIP, run a carrier lookup. It asks the routing databases which provider serves the number today and returns the line type: mobile, landline or VoIP. The digits won't tell you. In the US and Canada, VoIP providers draw numbers from the same area codes as everyone else, and a number can be moved to a VoIP provider without changing a digit.

Check one number in three steps

1. Write the number in E.164 format, with a + and the country code: +16502530000. The free phone number validator does this and tells you straight away if the number can't exist.
2. Run a carrier lookup. This is a paid query against live routing data, usually a fraction of a cent.
3. Read the line type. voip means an internet calling provider serves the number. You'll often get the provider's name too.

We ran this on +16502530000, a California number. The free numbering-plan check said "mobile or landline", the most it can say about a US number. The carrier lookup said VoIP, with the provider's name. That gap is the whole reason the lookup exists.

Why the number itself doesn't give VoIP away

A VoIP number is an ordinary phone number served over the internet. The FCC calls services that connect to the regular phone network "interconnected VoIP", and they hold numbers like any other carrier. Three things make them invisible to a simple check:

Reason	What it means
Shared number ranges	In North America, VoIP providers get numbers from the same area codes and exchanges as mobile and landline carriers.
Porting	A mobile or landline number can be moved to a VoIP provider and keep its digits.
Resold numbers	Many VoIP apps rent numbers from wholesale carriers, so the original block holder is a carrier you've never heard of.

A few countries do set aside VoIP ranges. The UK's 056 prefix is one, and Google's open-source libphonenumber labels those numbers VOIP from the range alone. But most VoIP numbers in the UK, as in the US, sit in ordinary geographic or mobile ranges.

Why VoIP numbers matter

VoIP numbers are cheap, quick to create, and easy to throw away. That makes them useful for ordinary people and businesses, and also for anyone who wants many accounts. The usual reasons to check:

• Sign-ups and free trials. Many products send a one-time code by SMS and treat VoIP numbers as higher risk, because one person can create many.
• Payments and account recovery. Fraud checks often weigh a VoIP number differently from a long-held mobile.
• SMS campaigns. Some VoIP numbers can receive texts and some can't, and delivery can be less predictable than on a mobile network. See validating phone numbers for SMS.
• Lead quality. A list of "mobile numbers" that turns out to be mostly VoIP tells you something about where the list came from.

Free check vs carrier lookup for VoIP

Question	Free format check	Carrier lookup
Can the number exist?	Yes	Yes
VoIP in a dedicated VoIP range (e.g. UK 056)	Yes	Yes
VoIP in an ordinary US/Canadian range	No	Yes
Number ported to a VoIP provider	No	Yes
Provider name	No	Usually
Cost	Nothing	A fraction of a cent per number

For the full picture of what the free check covers, see free phone number validator, and for carriers in general, phone carrier lookup.

Should you block VoIP numbers?

Usually flag, don't block. Real customers use VoIP: small businesses on internet phone systems, remote teams, people with a Google Voice number they've had for years. Blocking every VoIP number turns some of them away.

A sensible rule set:

1. Reject numbers that can't exist. No lookup needed; the format check catches them.
2. Flag VoIP numbers for a second step, such as email confirmation or a manual review, on sign-ups where abuse is a real cost.
3. Leave VoIP out of SMS-only campaigns if your messaging provider reports poor delivery to them.
4. Keep VoIP numbers for calling lists unless your own results show they don't connect.

Whatever you decide, write the rule down and apply it the same way every time. A lookup gives you the data; the policy is yours.

Find VoIP numbers across a whole list

For a list, you want a line-type column you can filter on. In SimpleVerifier:

1. Export a CSV with a phone column. Emails can sit in the same file and get a mailbox check in the same pass.
2. Upload it on the verifier. Numbers without a country code are read as US numbers.
3. Every valid number gets its E.164 form, country and numbering-plan type.
4. On the Email + Phone plan ($49.99/month), every number also gets a live carrier lookup, adding phone_carrier and phone_line_type, where VoIP numbers show up as voip. You get 5,000 lookups a month, and failed lookups don't count.
5. Filter the download on phone_line_type to pull out, flag or keep the VoIP rows.

The $29.99 Pro plan gives unlimited format and numbering-plan checks, which is enough for catching broken numbers but not for spotting VoIP in North America. To try a single number now, use the free phone number validator.