A phone carrier lookup tells you which telecommunications provider currently serves a phone number — AT&T, Verizon, T-Mobile, Rogers, Bell, Telus, or a VoIP carrier like Google Voice. But modern carrier lookup APIs go far beyond the carrier name. They reveal line type (mobile, landline, VoIP, toll-free), the current carrier (ported numbers show their new carrier), and whether the number currently has an active carrier assigned — data that drives smarter, more compliant communication decisions.

What Data Does a Carrier Lookup API Return?

Carrier name — the current serving carrier after any number porting (e.g. T-Mobile, AT&T, Verizon, Rogers)
Line type — mobile, landline, VoIP or toll-free
Porting — reflected automatically: the carrier shown is the current one, so a ported number shows its new carrier
Number status — Valid (follows the NANP and is assigned to a phone carrier, i.e. active) or Invalid (does not follow the NANP, or is not assigned to a carrier, i.e. inactive)
Geolocation — city, state, ZIP code, and timezone for US and Canada numbers
Network domain — the carrier’s MMS/SMS gateway domain for direct message routing

Note: RealValidito’s Phone Carrier Lookup does not return DNC status or TCPA litigator information — that requires a separate DNC Lookup call. Both services are available via API or CSV upload; run both for compliance screening, or use Phone + DNC Lookup to do both in one call.

Why Line Type Matters More Than Ever

The TCPA prohibits auto-dialed or pre-recorded calls to mobile numbers without prior express written consent. If your list contains landline numbers mistakenly labeled as mobile — or mobile numbers that were ported to a VoIP service — you can unknowingly violate TCPA while also wasting campaign budget calling unreachable numbers.

For SMS campaigns, only mobile numbers can reliably receive text messages. Landlines cannot receive SMS. VoIP numbers may or may not accept SMS depending on the provider. Filtering by line type before every campaign send is essential for both deliverability and compliance.

Read our full guides on What is a Landline Number and How to Detect VoIP Numbers for more detail on line type filtering.

How Local Number Portability (LNP) Affects Carrier Lookups

In the US and Canada, consumers can keep their phone number when switching carriers — this is Local Number Portability (LNP). A number originally assigned to Verizon may now be served by T-Mobile. A number that started as a landline may have been ported to a mobile carrier and can now receive SMS.

A static carrier database lookup returns the original carrier. An LNP-aware carrier lookup returns the current serving carrier — which is what matters for delivery, compliance, and billing. RealValidito Phone Lookup data is updated daily, so ported numbers return their current carrier.

Learn more about how porting affects your contact data in our guide: What is Number Porting? How to Detect Ported Numbers Before You Dial.

Carrier Lookup API: Common Use Cases

Use Case	Why Carrier Data Is Needed
SMS marketing	Confirm mobile line type; avoid sending SMS to landlines or VoIP
TCPA compliance	Separate mobile from landline before using auto-dialers
Fraud prevention	Flag VoIP numbers associated with high-fraud patterns
CRM enrichment	Tag contacts by carrier and line type for segmentation
Lead scoring	Mobile numbers on major carriers score higher for reachability
Number porting detection	Identify contacts who switched carriers since last validation
List hygiene	Remove inactive numbers with no carrier assigned

Understanding Active vs Inactive Numbers

One of the most valuable data points returned by a carrier lookup API is whether the number is active (assigned to a carrier); in RealValidito’s results this is part of the Valid / Invalid status:

Active — a carrier has been assigned to this number. The number is assigned to a carrier (Valid); Phone Lookup does not check whether it can receive calls or SMS right now
Inactive — no carrier is currently assigned to this number. It cannot receive calls or SMS regardless of its format or previous history

Note that active only means a carrier is assigned to the number — it does not indicate whether someone is currently using the number or whether the number has been disconnected by its owner. For more detail, see our guide on What is a Phone Validator.

Integrating the RealValidito Carrier Lookup API

RealValidito’s REST API returns carrier (ported numbers show their new carrier), line type, and number status for US and Canada numbers in a single HTTP request. The API is designed for high-volume integration into CRMs, web forms, call center software, and custom applications.

POST https://app.realvalidito.com/phonelookup/validate
Response:
{
  "status": "success",
  "data": {
    "704*******": {
      "status": "Valid",
      "phone_number": "+1704*******",
      "national_format": "(704) ***-****",
      "country_prefix": "1",
      "number_type": "Mobile",
      "zip": "28201",
      "area": "",
      "city": "CHARLOTTE",
      "state": "NC",
      "country": "US",
      "timezone": "EST (America/New_York)",
      "network_name": "CELLCO PARTNERSHIP DBA VERIZON",
      "network_type": "WIRELESS",
      "network_domain": "704*******@vtext.com"
    }
  }
}

See the full API documentation for authentication, request format, and response field definitions.

Carrier Lookup vs DNC Lookup — What’s the Difference?

These are two completely separate services that serve different purposes:

Feature	Phone Carrier Lookup	DNC Lookup
What it checks	Carrier, line type, Valid/Invalid status	DNC screening data, TCPA litigators
Purpose	Deliverability and routing	Legal compliance
Combined option	Phone + DNC Lookup (one call)
CSV upload available	Yes	Yes (separate upload)
Update frequency	Daily	Regularly

For deliverability and compliance screening, run both — or use Phone + DNC Lookup, which does both in one call or one file. Or use Phone Lookup for carrier and line type and DNC Lookup for DNC screening and TCPA litigator status separately.

US vs Canada Carrier Coverage

The US and Canada share the NANP (North American Numbering Plan), meaning all 10-digit numbers follow the same format. RealValidito covers all major US carriers (AT&T, Verizon, T-Mobile, Comcast) and all major Canadian carriers (Rogers, Bell, Telus, Videotron, Shaw/Freedom) plus hundreds of regional and MVNO carriers.

Numbers from outside the US and Canada are not currently supported. Our database updates daily to reflect the latest carrier assignments, number activations, and porting changes.

Frequently Asked Questions

How accurate is the carrier lookup?

RealValidito Phone Lookup data is updated daily and reflects number porting, so you see the current carrier name and line type. Numbers ported very recently may take up to 24 hours to reflect in carrier records.

Can I look up carrier for a VoIP number?

Yes — VoIP numbers are identified and labeled as VoIP in the line type field. The carrier name returned will be the VoIP provider (e.g. Google Voice, Twilio, Bandwidth). VoIP numbers may or may not accept SMS depending on the provider’s configuration.

Does carrier lookup show who owns the number?

No. RealValidito returns carrier-level data only — it does not return the name, address, or any personal information about the number’s owner. This is carrier lookup, not reverse phone lookup.

How fast is the API response?

RealValidito typically returns carrier lookup results within 500 ms, making it suitable for real-time validation at the point of form submission or CRM entry.

Start With 1,000 Free Carrier Lookups

Create a free RealValidito account and validate your first 1,000 phone numbers instantly — no credit card required. The Phone Lookup API returns carrier name (ported numbers show their new carrier), line type, Valid/Invalid status, and geolocation in a single call.

For DNC and TCPA litigator checking, use the DNC Lookup service or Phone + DNC Lookup.

Phone Carrier Lookup API: Detect Line Type, Carrier & Porting Status in Real-Time