Skip to main content

​
Free Tool: Carrier & Line-Type Lookup Checker

The carrier & line-type lookup checker is a free, browser-side tool on the developer tools hub. Paste a number and it shows the detected line type — mobile, fixed line, toll-free, VoIP, or one of the rarer numbering categories — with a general SMS and voice reachability verdict for that type. No account required. The checker is a structural classification from the number’s format, built on the same E.164 analysis engine as the E.164 formatter. It does not perform a live carrier network (HLR) dip. For a definitive, billed lookup against a live network — reachability, ported carrier, SIM swap — use the authenticated Number Lookup API.

​
What the tool returns

For any valid, complete number, the tool resolves four fields: Depends means the numbering category itself is ambiguous — a range shared by fixed and mobile lines in some countries, a toll-free number whose SMS add-on may or may not be provisioned, or a VoIP range whose provider may or may not terminate SMS. The verdict reads from the numbering category, so it never overclaims certainty for a type that genuinely varies by carrier. An invalid or incomplete input resolves to no classification at all, rather than a guessed verdict.

​
How line type maps to compliance posture

Line type is the input to several tenant-owned controls on Orbit, so it is worth resolving before you put a number into a list or a flow:
  • VoIP lines carry disproportionate fraud and pumping risk. Treat a VoIP verdict as a flag to route the number through verification or step-up checks before trusting it as a contactable identity — the same signal that drives voice destination auto-blocks at the destination level.
  • Toll-free numbers are not SMS-reachable by default. US toll-free messaging requires a separate toll-free verification (TFV) approval before carriers accept the traffic, so a “Depends” SMS verdict on toll-free means verify first, then send.
  • Fixed lines cannot receive SMS unless the carrier has provisioned a text-enablement add-on. Consent captured against a landline is a liability for an SMS program — scrub it before capture.
  • Mobile numbers are the default SMS opt-in target: native reachability on both channels, with no extra carrier step.
This is the same posture the TCPA compliance checklist tool scores: knowing which class each number falls into is the prerequisite for configuring the gates it walks.

​
How this interacts with opt-in capture

Consent language like “reply STOP to opt out, HELP for help” only works on a channel the number actually receives. A STOP/HELP reply is interactive only if the endpoint can exchange SMS at all — a fixed line or unverified toll-free number cannot, which is why the suppression model treats line type as one of its inputs and why opt-out lists are scoped to the channel of the messaging service they attach to. Capture opt-in against the channel you actually intend to send on. The opt-out keyword flow (keyword lists, auto-reply rules) assumes an SMS endpoint; a number the checker flags as SMS-unreachable never enters a valid opt-in state for SMS programs.

​
Use at import time

Carriers block SMS addressed to fixed-line numbers outright, and deliverability to unverified numbers fails silently until the errors surface in your delivery logs. Scrub a CSV before you capture consent, not after:
  1. Run the list through the checker (or the Number Lookup API for a live verdict at scale) and drop fixed-line and premium-rate numbers.
  2. Mark VoIP and toll-free rows for verification or TFV before they enter a campaign.
  3. Import the cleaned roster through the import contacts flow — rows it still cannot parse land in the skipped-rows CSV.
Combine the scrub with the DNC scrub gate so registry-listed numbers are excluded at send time as well as at import.

​
See also