LRN lookup API for routing, porting and fraud checks
LRN lookup API from CallerAPI returns the location routing number, OCN, SPID, line type and port status for a US number in one GET request. Route on the switch that serves the number today, not the one its prefix suggests. The same response carries the spam score and the caller name. One credit per lookup, on plans from $25 a month.
Get an API key"carrier_info": {
"network": {
"carrier": "Example Wireless",
"type": "WIRELESS",
"ocn": "6214",
"spid": "6214",
"original": {
"carrier": "Example Telecom",
"spid": "9104"
}
},
"number": {
"lrn": "2129990000",
"mobile": true,
"ported": true,
"ported_date": "2026-03-14T18:22:05Z"
}
}LRN + OCN
plus SPID and line type, in one response.
2
carriers per answer: the original one and the one that serves the number now.
$25
a month to start, on the same plans as the caller ID API.
One dip. Three decisions.
A prefix tells you where a number was born. The dip tells you where it lives, and who carried it before.
Routing
The LRN of the switch that serves the number now. Route on it, and ported numbers stop landing on the wrong carrier.
Carrier identity
OCN, SPID, carrier name and line category, such as wireless, CLEC or ILEC. These are the fields teams usually look up in the LERG.
Porting
A ported flag, the port date and the original carrier. A fresh port just before a password reset is a classic sign of port-out fraud.
| Field in carrier_info | What it tells you |
|---|---|
| number.lrn | The switch to route the call to |
| network.ocn, network.spid | The carrier that serves the number now |
| network.type | The line category, such as WIRELESS or CLEC |
| network.original | The carrier and SPID before the port |
| number.ported_date | When the number last moved carriers |
| number.timezone | The local time zone, for calling hours |
Who runs a dip on every call
Wholesale carriers and CPaaS
In the US, the N-1 carrier owes the dip. Build it into least-cost routing instead of paying for misrouted calls.
Dialers and contact centers
The line category tells mobile from landline before you dial. That matters for consent rules on wireless numbers.
Fraud and risk teams
Read the port date, the carrier change and the spam score together, before you trust a one-time code.
LRNs are a North American routing concept. For mobile numbers in other countries, the carrier lookup API returns the live network from the HLR. Need the caller name with the dip? See the CNAM lookup API.
Route on the number's real home
Get a key, add ?hlr=true to a lookup, and read the LRN in the response. Routing millions of calls a month? Scope a volume deal.
Get an API key