LNP Dipping Service
Real-Time LRN Lookups for Carriers
Every call you route should be dipped first. proleneä's LNP dipping service returns the Location Routing Number for any dialed number in under 50 microseconds — over SIP, ENUM, HTTP or XML — so you route on the serving carrier, not the number block, and stop overpaying for termination.
What is an LNP dip?
An LNP dip — you'll also hear LRN dip, LRN lookup or number portability dip — is a real-time query that asks a Local Number Portability database one question: which switch serves this telephone number right now? The answer comes back as the Location Routing Number (LRN), a ten-digit number formatted like a phone number that identifies the serving switch.
Since numbers can be ported between carriers, the dialed number no longer tells you who serves the subscriber. Only the LRN does. Dipping before you route is how carriers, VoIP providers and dialers make sure each call goes to the right place at the right rate.
proleneä's dip response also carries the SPID, OCN, LATA and portability status, sourced from the NPAC — the authoritative record for every ported number in the North American Numbering Plan.
Why route on the LRN instead of the dialed number?
Routing on the dialed number sends the call toward the carrier that owns the number block — not necessarily the carrier that serves the subscriber. The call may complete, but wholesale termination is billed on the final serving carrier, so the invoice is higher than the rate deck suggested.
In almost every case, termination charged on the dialed number differs from termination charged on the serving carrier. If you want to manage cost, you have to dip and route on the LRN.
Most providers realize a 15% to 30% reduction in their termination bills once they start LNP dipping.
How you dip: SIP, ENUM, HTTP or XML
Use whatever your switch, SBC or dialer already speaks. Most customers are dipping within minutes of receiving credentials.
SIP Redirect Dip
Send the INVITE to proleneä; we answer with a 3xx redirect carrying the LRN in the Contact header (rn= parameter). Native to softswitches, SBCs and Class 4 platforms.
ENUM / DNS Dip
Standard e164.arpa-style NAPTR lookup against our ENUM servers. Trivial to enable in Kamailio, OpenSIPS, FreeSWITCH, Asterisk and most carrier switches.
HTTP / REST Dip
A simple GET with the dialed number returns LRN, SPID, OCN and LATA as plain text your application can parse in one line. Ideal for dialers, billing systems and applications outside the call path.
XML & Custom
XML request/response for legacy platforms, plus custom protocols built to your network's needs when nothing off-the-shelf fits.
Dip pricing that fits your traffic
Dialers spike, wholesalers run flat, and CLECs sit in between — so we price LNP dipping four ways and let you pick.
- Per dip — from $0.000015 per lookup, no minimum to get started.
- Volume-tiered — the rate falls as monthly dip volume grows.
- Peak CPS — pay for the calls-per-second you need, dip as much as you like within it. Built for high-volume, highly peaked dialer traffic.
- Unlimited — one flat monthly rate, no counting.
Every plan starts with a free interoperability period on the live production network — real data, real speed, no sandbox — available within minutes of our first conversation. See the full network specs and rate estimator →
Three ways to get your dips
Why carriers dip with proleneä
Built for dipping, not adapted for it
Proprietary lookup engine that exploits the dialed-number → LRN relationship directly, instead of a general-purpose protocol stack. That is where the microseconds — and the price — come from.
Handles dialer-shaped traffic
225,000 dips per second per server. Bursty, highly peaked call patterns don't degrade response time or get throttled.
NPAC-sourced, US & beyond
Coverage of the United States and its territories (Puerto Rico, USVI, Guam, American Samoa, N. Mariana Islands and more), with Canada, Mexico and other international portability data available — ask.
24 / 7 monitoring
Redundant, geographically diverse servers watched around the clock. Five-nines availability SLA — less than five minutes a year.
See your own dip traffic
Customer web portal with your historical dip volume and peak CPS, charted and downloadable, current to the last hour.
20+ years of number portability
proleneä has been running LNP infrastructure for high-traffic voice carriers since the early days of portability. About us →
LNP Dipping FAQ
What is an LNP dip (LRN dip)?
An LNP dip — also called an LRN dip — is a real-time database lookup that returns the Location Routing Number (LRN) for a dialed telephone number. The LRN identifies the switch that currently serves the number, which is what you need to route and rate a call correctly once numbers can be ported between carriers.
Why route calls on the LRN instead of the dialed number?
Routing on the dialed number sends the call toward the carrier that owns the number block, not necessarily the carrier that serves the subscriber today. The call may complete, but wholesale termination is billed on the final serving carrier, so the cost is often higher than expected. Dipping for the LRN and routing on it lets you pick the right route and rate; most providers see 15% to 30% lower termination bills once they start dipping.
What protocols can I use for LNP dipping?
proleneä answers LNP dips over SIP (redirect), ENUM (DNS NAPTR), HTTP and XML, and can build a custom protocol if your switch or dialer needs something else. Most customers are dipping within minutes of receiving credentials.
How is LNP dipping priced?
Four models: per dip (from $0.000015), volume-tiered, peak calls-per-second, or unlimited flat rate. A free interoperability period lets you test against the live production network before committing.
Can I run LNP dips on my own server?
Yes. In addition to dipping our cloud servers, proleneä can install its LNP dipping software on a server at your site so lookups never leave your network.
Can I convert a list of dialed numbers to LRNs without real-time dips?
Yes. proleneä's LRN Retrieval web tool lets you upload a file of telephone numbers and get back each number with its current LRN, SPID and OCN — useful for CDR analysis, rate-deck audits and route planning. Ask us for access.
Start Dipping Today — Free
Free interoperability period on the live production LNP network. Real data, real speed, no commitment.
Tell us your protocol and we'll have you dipping in minutes.