Carrier Lookup API
✓ Official Vendor SpecData EnrichmentContact EnrichmentapiKey1 EndpointsREST
For Agents
Resolve a US phone number to carrier name, line type (mobile/landline/VoIP), validity, and active status via a single GET /lookup call.
Use for: I want to look up the carrier for this US phone number, Check whether a number is mobile, landline, or VoIP, Validate a phone number entered on our signup form, Find out if 415-555-1234 is on Verizon
Not supported: Does not handle international phone validation, SMS sending, or voice calls — use for US carrier and line-type lookup only.
Carrier Lookup API resolves a US phone number to its underlying carrier metadata: carrier name, line type (mobile, landline, VoIP), number validity, and active status. It exposes a single GET /lookup endpoint that takes a phone number and an API key, making it a lightweight enrichment service for SMS routing decisions, contact data hygiene, fraud and bot detection, and form validation. Authentication is an API key passed as the `key` query parameter.
Install Jentic One Beta
Connect the Carrier Lookup API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Carrier Lookup API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
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Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Carrier Lookup API.
Identify the carrier behind a US phone number (Verizon, AT&T, T-Mobile, etc.)
Detect line type — mobile, landline, or VoIP — to inform SMS deliverability
Validate that a phone number is well-formed and reachable
Check whether a phone number is currently active
Filter out VoIP numbers in fraud-screening or signup-quality workflows
Use Cases
Patterns agents use Carrier Lookup API for, with concrete tasks.
★ Signup Form Phone Validation
Block signups using fake or VoIP-only phone numbers. On submission, call GET /lookup with the user-entered number; if the response says the number is invalid, inactive, or VoIP (depending on policy), reject or flag the registration. This catches throwaway numbers commonly used to evade per-account limits.
Look up the phone number a user just entered, and reject the form if line type is VoIP or active is false.
SMS Deliverability Routing
Route messages intelligently based on carrier and line type. Mobile numbers go via SMS; landlines and VoIP can be routed to voice or skipped entirely. The Carrier Lookup response provides the carrier name and line_type fields needed to make this routing decision per-recipient before submitting to a messaging gateway.
For each recipient phone number, call GET /lookup and only queue SMS messages to those returned as line_type=mobile.
CRM Contact Data Hygiene
Run a periodic enrichment pass over a CRM's phone column to mark inactive or invalid numbers and append carrier metadata. Each contact gets a single GET /lookup request, and the response fills carrier, line_type, valid, and active fields back onto the record. This avoids wasting outbound calls and SMS attempts on stale numbers.
Iterate the CRM contacts table, call /lookup for each phone, and update the record with carrier, line_type, and active status.
AI Agent Phone Verification via Jentic
Plug Carrier Lookup into an agent through Jentic so a question like 'is this number a real mobile?' becomes a single tool call. Jentic returns the GET /lookup operation schema, holds the API key in its vault, and lets any framework (LangChain, CrewAI, MCP) issue the lookup without managing the query parameter manually.
Through Jentic, look up phone number 415-555-1234 and return carrier, line_type, and active fields.
Key Endpoints
1 endpoints — carrier lookup api resolves a us phone number to its underlying carrier metadata: carrier name, line type (mobile, landline, voip), number validity, and active status.
METHOD
PATH
DESCRIPTION
GET
/lookup
Look up carrier information for a US phone number
GET
/lookup
Look up carrier information for a US phone number
Why Jentic?
Three things that make agents converge on Jentic-routed access.
Credential isolation
Carrier Lookup API keys are stored encrypted in Jentic's vault. Agents receive scoped execution rights only — the key is injected into the `key` query parameter at request time and never enters the agent's prompt or chat logs.
Intent-based discovery
Agents search Jentic by intent (e.g., 'look up phone carrier' or 'detect voip number') and Jentic returns the GET /lookup operation with its input schema, so the agent supplies the right parameters without reading docs.
Time to first call
Direct Carrier Lookup integration: 1-2 hours to wire the GET /lookup endpoint, parse the response, and add basic retry handling. Through Jentic: under 10 minutes — search, load, execute.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Carrier Lookup API through Jentic.
What authentication does the Carrier Lookup API use?
Carrier Lookup uses an API key passed as the `key` query parameter on every request. Through Jentic the key is stored encrypted in the credential vault and injected into the URL at request time, so the raw key never appears in chat logs or agent prompts.
What does the Carrier Lookup API return for a phone number?
The /lookup endpoint returns the carrier name (Verizon, AT&T, T-Mobile, etc.), the line type (mobile, landline, VoIP), a validity flag indicating whether the number is well-formed, and an active flag indicating whether the line is in service. This combination supports both routing and fraud-screening use cases.
Does Carrier Lookup work for non-US phone numbers?
The API is documented as a US phone number lookup service. Coverage outside the US is not part of the OpenAPI surface; for international validation pair Carrier Lookup with another provider that covers your target geographies.
Can I use Carrier Lookup to detect VoIP numbers?
Yes. The line_type field returned by GET /lookup will indicate `voip` for VoIP numbers, `mobile` for cellular, and `landline` for fixed lines. This is the standard signal used by signup-fraud screens to filter out disposable or virtual numbers.
What are the rate limits for the Carrier Lookup API?
The OpenAPI specification does not declare numeric rate limits. Limits are tied to the plan associated with your API key — keep concurrent requests modest and back off on 429 responses. Refer to https://www.carrierlookup.com/carrier-lookup-api-integration/ for plan tiers and quotas.
How do I look up a number through Jentic?
Run `pip install jentic`, then use Jentic's search to find the lookup operation with the query "look up phone carrier", load the schema, and execute with `{"number": "4155551234"}`. Jentic calls GET /lookup with your API key from the vault and returns carrier, line_type, valid, and active fields.
Can I batch-process a list of phone numbers?
The API exposes a single GET /lookup endpoint that takes one number per call. To process a list, iterate sequentially or in modest concurrency from your application; the API does not provide a built-in bulk endpoint, so batching is the caller's responsibility.
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