What is Phone Number Lookup?
Phone Number Lookup, is a Bandwidth API service that provides carrier intelligence data for phone numbers in the mainland United States, Alaska, Hawaii, District of Columbia, and Canada, including those that are not on the Bandwidth network.
Note: Bandwidth also offers an advanced version of Phone Number Lookup, called Dynamic Number Intelligence (DNI).
What data does Phone Number Lookup provide?
Each Phone Number Lookup API response provides the following standard number data:
Country code
Line type (Fixed, Mobile, or VOIP)
Normalized Messaging provider*
Normalized Voice provider*
Note: Due to the Canadian Porting Authority restrictions, the messaging and voice provider data is not available for Canadian numbers.
What is a normalized provider name?
With hundreds of different provider names across the US, it can be challenging to determine which tier 1 carrier operates under each of them (e.g., Teleport Communications America, LLC is AT&T, while Voicestream GSM, LLC is T-Mobile). The Phone Number Lookup API takes out the guesswork by “normalizing” them to display the name of the correct tier 1 carrier by default.
What is the difference between voice and messaging providers?
A number's voice carrier (who owns and routes calls) is sometimes different from its messaging provider (who routes SMS/MMS). Bandwidth returns both separately. This data can be useful if you’re routing messages based on the provider, managing carrier-specific throughput limits, or validating that a number is truly textable.
What is the difference between Synchronous or Asynchronous Bulk Phone Number Lookup API?
You can look up numbers (TNs) using Synchronous or Asynchronous Bulk API, whichever fits your use case best. All numbers must be submitted in the E.164 format.
| Synchronous | Asynchronous Bulk |
Endpoint | POST .../phoneNumberLookup | POST .../phoneNumberLookup/bulk |
Use case | Real-time, low-volume lookups (e.g., onboarding, MFA validation) | Large-volume lookups (e.g., weekly list audits, pre-campaign hygiene runs) |
Max TNs per request |
100 |
15,000 |
Max requests per second |
75 |
75 |
How is Phone Number Lookup billed?
You’ll be billed at your contracted rate for each successful phone number lookup. If a number can’t be found (returned as a failed/no-match result), you won’t be billed for it. If you submit the same number in multiple requests, you’ll be billed multiple times.
If you’re on the DNI plan, you’ll receive a fixed monthly recurring charge (MRC) based on your messaging volume rather than per lookup. For a detailed overview of your voice, messaging, or number charges, see Charges reports.
To enable Phone Number Lookup on your account, please contact your Account Manager or open a ticket with your Bandwidth Support Team.