LRN Lookup: Local Routing Numbers

What is LRN?

A Local Routing Number (LRN) is a 10-digit number that identifies the switch serving a telephone number. When a number is ported from one carrier to another, the LRN changes to reflect the new carrier.

Without LRN lookup, you only know the original carrier based on the area code and prefix. With LRN lookup, you know the current carrier regardless of porting history.

How LRN Works

The NPAC (Number Portability Administration Center) maintains the authoritative database of which carrier serves each ported number. LRN lookup queries this database to return:

• LRN — The routing number for the serving switch
• OCN — Operating Company Number identifying the carrier
• Carrier Name — Human-readable carrier identification
• Line Type — Wireless, landline, or VoIP
• Ported Status — Whether the number has been ported

LRN Activation Date (Exclusive)

LRN Activation Date shows when a phone number was last ported to its current carrier. This exclusive data point is invaluable for fraud detection:

• SIM swap detection — Recently ported numbers may indicate account takeover
• Trust scoring — Long-term carrier relationships indicate stability
• Risk assessment — New activations warrant additional verification

LRN Use Cases

Call Routing

Route calls efficiently by knowing the actual serving carrier:

• Choose least-cost routes based on terminating carrier
• Avoid failed calls due to incorrect carrier assumptions
• Optimize voice quality by selecting direct routes

SMS Delivery

Improve SMS delivery rates:

• Route messages through appropriate carrier gateways
• Identify line type before sending (wireless vs. landline)
• Avoid wasted messages to non-SMS-capable numbers

Fraud Prevention

Screen for suspicious porting activity:

• Flag recently ported numbers for additional verification
• Detect potential SIM swap attacks
• Identify VoIP numbers (often higher fraud risk)

API Example

curl -X POST https://api-service.verirouteintel.io/api/v1/lrn \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"phone_number": "15551234567"}'

# Response
{
  "data": {
    "phone_number": "15551234567",
    "lrn": "5551230000",
    "carrier": "Verizon Wireless"
  },
  "success": true
}

LRN vs. CNAM

Recommendation: Use both LRN and CNAM together for comprehensive phone intelligence.