Use this as a lighter-weight fraud signal than check_carrier_identity: how many distinct business addresses and phone numbers a carrier reports across FMCSA's independent records of it (census, licensing and insurance, crash reports). Several different addresses on one carrier is a common re-registration tell. Billed whenever the USDOT number resolves.

Use this to check one applicant carrier against a roster of carriers you already work with — e.g. catching one you previously cut for a revocation or suspension trying to re-enter under a new USDOT number. Returns whether it's linked to any roster member and which ones, never a carrier outside your own roster. Metered: a base price plus a per-roster-entry price, both shown in get_catalog; billed whenever the applicant resolves, whether or not it matches anything on your roster.

Use this when a carrier looks suspicious — a name change, a new USDOT number tied to an old fleet, a business you suspect re-registered after a revocation — and you need the full evidence: every other USDOT number sharing a contact identifier with it, and whether any of them carries a revocation or suspension motive. Call the free screen_carrier_identity first if you only need the flag and a count. Billed whenever the USDOT number resolves, even with no links found.

Use this when you already suspect two specific carriers (by USDOT number) are the same operation under different paper and want it confirmed, without receiving any information about a carrier you didn't name. Returns only linked true/false and, when true, the shared cluster_id — never a member list. Billed whenever both USDOT numbers resolve, whether or not they turn out to be linked; supplying the same number twice is free.

Use this once you have a USDOT number (from lookup_carrier or search_carriers) and need to see how a carrier's safety profile has changed over time: historical snapshots and a field-level changelog, optionally filtered to changes on or after a given date. Billed only when history exists for the number; an unknown number is free.

Use this when you already have a carrier's USDOT number and need its current profile: safety rating, authority status, insurance flags, fleet size. Returns Active, Inactive, and Pending carriers alike. Billed only when the number resolves to a real carrier; an unknown number is free.

Use this when you don't have a USDOT number yet and need to filter carriers by state, safety tier, authority status, or cargo type — for example, every carrier with an unsatisfactory rating in a given state. Capped at 100 rows per call, Active carriers only by default. Billed only when at least one carrier matches; a zero-row result is free.