SMS least cost routing (LCR): how it works and how to set it up

Every SMS business buys messages from several suppliers and sells them to its own customers. Least cost routing (LCR) decides which supplier carries each message so you keep a margin on every one. This guide explains how SMS LCR works, why the cheapest route is not always the best, and what a good SMS switch should do for you.

What is SMS least cost routing?

SMS least cost routing is the logic inside an SMS switch that chooses, for each message, the supplier (route) with the lowest buy price for that destination, while still meeting your quality rules. You load each supplier's rate plan, the switch looks up the destination of every message, and it sends the message through the cheapest route that is allowed for that customer.

Without LCR you would pick suppliers by hand per country. With hundreds of networks and rates that change every week, that quickly becomes impossible to manage and margin leaks away.

How SMS LCR picks a route

Number clean-up. The destination is normalised (a leading + or 00 is removed) so every format gets the same rate.
Rate lookup. The switch finds the longest matching prefix, or the mobile network (MCC/MNC), in the customer's sell plan. That is what you charge.
Route selection. It compares the buy rates of the suppliers allowed for that destination and picks one according to the routing strategy.
Charge and send. The customer's balance or credit limit is checked, the message is charged and submitted to the supplier.
Reroute on failure. If the supplier rejects the message, the switch can try the next route in the list.
Delivery report. The DLR comes back from the supplier and is passed to your customer, and it also tells you how well that route really delivers.

Routing strategies compared

Strategy	How it chooses	Best for
Least cost	Lowest buy rate for the destination	Price-sensitive bulk traffic
Failover	A fixed order; the next route is used only when one fails	Traffic that must get through, such as OTP
Round robin	Spreads messages across several routes in turn	Balancing load and testing new suppliers
Quality-based	Prefers routes with better delivery results	Customers who pay for premium delivery
Static	Always the same route	Dedicated or contracted routes

Most SMS businesses mix them: least cost for marketing traffic, failover or quality-based for OTP and banking, and static routes for customers with a dedicated supplier.

Why the cheapest route is not always the best

Delivery rate. A route that is 20% cheaper but delivers 70% of messages costs you more per delivered SMS than a route that delivers 98%.
Sender ID. Some cheap routes replace or drop the alphanumeric sender ID, which breaks OTP and brand messages.
Speed. One-time passwords expire. A route that delivers in minutes instead of seconds is useless for OTP.
Grey routes. Very low prices often mean unofficial paths that can be blocked by the operator at any time.

That is why good SMS LCR combines price with quality data from delivery reports, and lets you set different strategies per customer and traffic type.

Ported numbers, HLR and MNP lookups

In many countries people keep their number when they change operator (mobile number portability, MNP). The prefix then points to the wrong network, and you may pay or charge the wrong rate. An HLR or MNP lookup asks which network the number belongs to today, so the switch can route and rate it by the real MCC/MNC. It costs a little per lookup, so it is usually used for destinations where network prices differ a lot.

Protecting your margin

Flag routes selling below cost. When a supplier raises a price, routes can turn negative overnight. A margin dashboard should show this immediately.
Bill in real time. Charging each message as it is accepted, with credit limits for prepaid and postpaid customers, stops unpaid traffic from piling up.
Bill per segment. Long and Unicode messages are split into parts; each part should be charged.
Watch for SMS pumping. Sudden spikes, new countries or sequential numbers are signs of artificially inflated traffic that you would otherwise pay suppliers for.

Setting up SMS LCR step by step

Import supplier rate plans (CSV) and check the preview before you apply them.
Create customer sell plans with your margin per destination and currency.
Build routing rules by prefix or MCC/MNC, with a priority and a strategy for each.
Test with a route simulator to see which supplier a number will use before sending real traffic.
Send test messages and check delivery reports, speed and sender ID per route.
Review margins daily and adjust routes as supplier rates and quality change.

SMS LCR in the LCR ONE SMS Switch

The LCR ONE SMS Switch routes every message by prefix or MCC/MNC with five strategies (least-cost, failover, round robin, quality-based and static), reroutes on failure and has a route simulator. It charges each message in real time with credit limits, bills long messages per segment, supports HLR/MNP lookups and shows a margin dashboard that flags routes selling below cost. It runs on your own server, with SMPP 3.4 and an HTTP API.

See the SMS Switch → Book a free demo

FAQ

What does LCR mean in SMS?

LCR means least cost routing: the switch picks, for each message, the supplier with the lowest buy price for that destination that is allowed by your routing rules.

Is least cost routing good for OTP messages?

Usually not on its own. OTP needs fast, reliable delivery with the correct sender ID, so most businesses use failover or quality-based routing for OTP and least cost for bulk marketing traffic.

What is MCC/MNC routing?

MCC is the mobile country code and MNC the mobile network code. Routing by MCC/MNC lets you choose a supplier and price per mobile network instead of only per country or prefix.

Do I need HLR lookups for SMS LCR?

Only where numbers are often ported and network prices differ. An HLR or MNP lookup tells you the real network of a number so you can route and rate it correctly.

How do I know if a cheap route is really cheaper?

Compare the cost per delivered message, not the price per message sent. Use delivery reports to measure each route's delivery rate and speed.

Last updated: 26 October 2026 · LCR ONE