Mobile number portability (MNP) lets people keep their number when they change operator, so the prefix of a number no longer tells you for sure which network serves it. For wholesale voice this matters because termination rates differ by operator: carriers either run an MNP lookup for the current network before routing (an MNP dip) or bill by the original prefix and absorb the difference.
Why portability affects routing
Rate decks group prefixes into operator breakouts, such as Mobile Operator A and Mobile Operator B. When a customer ports a number from A to B, the number still starts with A's prefix but calls must reach B's network. If the operators charge different termination rates, a carrier that bills you at A's rate pays B's rate, or the other way round. In markets with a high share of ported numbers, this changes the real cost of a route.
How networks route ported numbers
| Method | How it works |
|---|---|
| All call query | The originating or transit network checks a portability database on every call and routes straight to the current operator |
| Query on release | The call goes to the original operator first; if the number has left, it is released back and the sender queries the database |
| Onward routing | The original operator receives the call and forwards it to the new operator, usually for a fee |
Which method is used depends on the country and on each carrier. A query is often called a "dip". After a dip, many networks add a routing number in front of the dialed number so the next switch knows where to send the call.
Billing models for ported numbers
- Billing by prefix: you pay the rate of the operator that originally owned the prefix. Simple and predictable, but the seller carries the risk, which may be priced into the rate.
- Billing by real network: the seller dips each number and bills by the actual operator. More accurate, but the rate on your CDRs may not match the prefix you expected. Some sellers charge a small fee per dip.
- Blended rate: one mobile rate for all operators, which removes the issue for you.
Ask which model applies before comparing rate decks; otherwise you compare different things.
Effects on quality and disputes
- A route direct to one operator may fail on numbers that have ported away, lowering ASR. Good routes dip before sending.
- Onward routing adds a hop and can add post-dial delay.
- Billing by real network is a common source of billing disputes when your CDRs are rated by prefix and the seller's by network. Agree the method in writing.
Looking up numbers yourself
For campaigns or high value traffic, you can check the current network of mobile numbers before dialing with an MNP or HLR lookup service. It helps you route each call to the best operator route and remove invalid numbers. The HLR lookup guide explains what these lookups return, and MCC and MNC codes explains how networks are identified.
Routes with clear portability terms
When you request VoIP termination for operator specific routes, ask us how ported numbers are routed and billed; we confirm it with the carrier. Request a voice route.
Frequently asked questions
What is an MNP lookup?
An MNP lookup checks which operator currently serves a mobile number, after any porting. It queries a national portability database or a lookup provider and returns the current network, usually as MCC and MNC codes or a routing number. Carriers use it to route calls to the right operator and to bill by the real network.
What is the difference between an HLR lookup and an MNP lookup?
An MNP lookup returns the operator that currently holds the number, from portability data. An HLR lookup queries the mobile network itself and can also show whether the number is active and, in some cases, reachable. HLR lookups usually cost more; MNP lookups are often enough for routing and for cleaning lists.
Is there a free MNP lookup?
Some lookup providers offer free trial credits, and some regulators or operators publish simple portability checks for consumers. For call routing at volume you need a paid service with an API, or a carrier that dips each call, because free tools are usually limited to a few manual checks and are not built for automated use.
Can I run a bulk MNP lookup on a number list?
Yes. Most lookup providers accept bulk files or batch API calls and return the current operator for each number, often with validity information. Running a list through an MNP or HLR lookup before a campaign removes invalid numbers, keeps ASR up and lets you send each call to the route for the right operator.
What is a routing number in number portability?
After a portability query, many networks put a routing number, a short prefix that identifies the current operator, in front of the dialed number. The next switch in the chain reads that prefix to send the call to the right network. The format and use of routing numbers differ from country to country.
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