How to Check If a Number Is VoIP (3 Easy Ways)

When a verification code never arrives, the problem often isn’t the website or your connection. It’s the number. Many services quietly refuse to send codes to VoIP numbers, and from the outside a VoIP number looks exactly like a mobile one.

Luckily, it only takes a minute to check. Here are three ways to find out whether a number is VoIP, from the quickest to the most reliable, and what to do with the answer.

Why it matters

Phone numbers come in three main types: mobile numbers issued by a carrier on a SIM card, fixed VoIP numbers tied to a phone line or device, and non-fixed VoIP numbers created online through apps like Google Voice or TextNow. Websites that verify accounts by SMS usually accept mobile numbers and often block VoIP ones, especially non-fixed VoIP. If you’re not sure how the types differ, start with our guide to VoIP vs non-VoIP numbers.

Method 1: Use a free carrier lookup tool

The easiest way to check a single number is a free online lookup.

1. Open a free phone lookup tool such as Phone Validator or Real Phone Validation.
2. Enter the full number, including the country code.
3. Look at the line type (sometimes called phone type) and the carrier in the results.

How to read the result:

• Mobile or wireless, with a mobile network as the carrier: the number is non-VoIP.
• VoIP: the number is VoIP. Some tools also tell you whether it is fixed or non-fixed VoIP.
• Landline: a fixed phone line, which usually can’t receive SMS codes at all.

Free tools are perfect for checking a number or two. For hundreds of numbers, or checks built into your own sign-up flow, use an API instead.

Method 2: Use a phone lookup API

Businesses check numbers automatically with phone-intelligence APIs, and this is exactly what many websites do behind the scenes when you sign up. Twilio’s Lookup API, for example, has a Line Type Intelligence option that returns each number’s type:

curl -X GET "https://lookups.twilio.com/v2/PhoneNumbers/%2B15017122661?Fields=line_type_intelligence" \
  -u $TWILIO_API_KEY:$TWILIO_API_SECRET

The response includes the carrier name and a type field such as mobile, landline, fixedVoip or nonFixedVoip. A result of nonFixedVoip is the one most verification systems reject. Lookup APIs are paid, per-request services, so they make sense when you check numbers at scale.

Method 3: Look for the telltale signs

You can often tell without any tool at all. A number is almost certainly VoIP if:

• You got it from an app or website (Google Voice, TextNow and similar “second number” apps hand out non-fixed VoIP numbers).
• You received it instantly online, without a SIM card or a carrier contract.
• Sign-up forms reply with messages like “this number can’t be used” or “please use a mobile number”.
• Codes from some services arrive while codes from stricter ones (banks, payment apps, marketplaces) never do.

The signs are a useful hint, but only a lookup tells you for certain.

What the result means

Need a number that passes the check?

If your number turned out to be VoIP, you don’t need a new phone contract. PVADeals rents real non-VoIP numbers from major carriers in the United States, the United Kingdom, Canada, Hong Kong, Indonesia and Australia. A carrier lookup shows them as mobile numbers, because that is what they are.

• Rent a short-term number for 20 minutes, from $0.09, for a one-off code.
• Rent a long-term number for 3 to 30 days if you’ll need it again.
• If an eligible number receives no SMS, its cost comes back automatically as store credit.

Read more about getting a temporary phone number for verification, or see the prices.