For most MVNOs, roaming is somebody else’s problem.
The host operator or the hub handles the agreements, the clearing and the settlement. Once a month a statement arrives. Someone in finance checks that the total looks roughly right, and it gets paid.
That arrangement works well enough, until it doesn’t. As margins get thinner and more non-telecom brands enter mobile, I believe roaming is becoming one of the least examined costs in the MVNO business.
Why MVNOs pay roaming charges they never verify
Every time a subscriber uses a partner network abroad, that network records the usage and bills the home network for it. In the GSM world those records travel as TAP3 files, the GSMA format defined in TD.57. They are the actual evidence behind every roaming charge: which subscriber, which network, which service, how much, at what rate.
Most MVNOs never see those records. They see a total.
A total can’t tell you whether a rate was applied that doesn’t match the agreement. It can’t tell you whether records were duplicated, whether a data session was charged at the wrong tariff, or whether usage was billed to the wrong zone.
I know of an MVNO that received SMS records from its host operator priced one decimal place higher than the contract said. Every message was charged at ten times the agreed rate. Nothing about the volumes looked unusual. Only the price on each individual record was wrong, and no monthly total would ever have shown it. It wasn’t roaming traffic, but it’s exactly the kind of error that hides in roaming settlement, where there are more partners, more tariffs and more records.
You can’t dispute what you can’t see. And roaming disputes don’t stay open forever: RAP, the Returned Account Procedure, is how incorrect records are formally returned to a partner, and it runs within a fixed window. By the time an aggregated statement raises a question, that window has often already closed.
None of this requires anyone to act in bad faith. Roaming settlement involves many parties, many agreements and a lot of records. Errors happen. The question is simply who is positioned to catch them.
Light MVNO or full MVNO: who actually receives the TAP3 files
A full MVNO, MVNEs, MVNAs with its own IMSI range receives TAP3 files directly, so it can verify them if it chooses to.
A light MVNO usually roams on its host’s identity. The TAP3 records go to the host, and the MVNO sees only the wholesale roaming charge passed on to it. Often it has no contractual right to the records underneath. That makes the exposure harder to see, not smaller.
For light MVNOs, visibility starts in the wholesale agreement. Record-level access to roaming usage is worth negotiating at contract signature or renewal, when you have leverage, not after a dispute, when you don’t.
Roaming fraud moves faster than TAP3: what NRTRDE was built for
The industry understood long ago that roaming abuse moves faster than monthly billing. That is why the GSMA introduced NRTRDE, defined in TD.35, near real-time roaming data exchange. Visited networks share usage records within four hours, so the home network can spot a stolen SIM or a sudden spike in premium-rate calls before the damage compounds.
Large operators have fraud teams watching those feeds. Many MVNOs have nobody watching. For them, the first sign of a roaming fraud incident is often the invoice itself, long after anything could have been done about it.
VoLTE roaming is the fraud monitoring blind spot
As 2G and 3G networks are switched off, roaming voice is moving to VoLTE. VoLTE roaming is the least monitored part of most MVNO roaming estates.
Under S8HR (S8 home routing), the visited network holds no IMS elements for roaming subscribers, so it generates no IMS accounting records to send home. There is no NRTRDE-style feed for VoLTE, and the industry’s reasoning has been that the home operator already has what it needs in its own IMS records and controls call routing in any case.
For an MVNO relying on someone else’s platform, it can mean that roaming voice is simply the part nobody monitors.
VoLTE roaming charging is also more complex than it looks. Originating and terminating services can be charged differently, different traffic types travel with different QCI values, and certain bearer traffic shouldn’t be charged at all. Every one of those rules is a place where a record and an agreement can quietly disagree.
The new MVNOs will inherit this without noticing
The industry is right to be excited about banks, retailers, travel brands and IoT providers embedding connectivity into what they already sell. For many of them, roaming is the headline benefit: a premium account that works abroad, a travel eSIM, a fleet that crosses borders.
Nobody at a retailer is asking about TAP records. Nobody at a bank is watching NRTRDE alerts. These brands will inherit roaming costs, roaming fraud exposure and roaming disputes without necessarily knowing that any of those things exist.
Connectivity may become invisible to the customer. It shouldn’t become invisible to the company paying for it.
Roaming monitoring without a roaming department
Historically, verifying roaming meant clearing-house contracts, specialist staff and in-house systems. That was disproportionate for most MVNOs, so the rational choice was to trust the statement.
That equation has changed. Record-level monitoring can now sit on a platform rather than inside your organisation. The platform checks records against agreed rates, flags anomalies, surfaces usage in near real time, and covers VoLTE alongside traditional roaming. It doesn’t replace the host or the hub. It gives you a way to check their work.
If you’re not sure where you stand, four questions are worth asking your host operator or hub:
- Do we receive record-level roaming data, or only totals, and does our contract give us the right to it?
- Who sees near real-time roaming alerts for our subscribers, and how quickly does anyone act on them?
- How is VoLTE roaming monitored for our subscribers?
- When did anyone last reconcile our roaming invoice against the agreed rates, record by record?
If the answers are vague, that tells you something too.
The cost you outsourced is still yours
Roaming used to be the operator’s problem. Increasingly, it’s the brand’s problem, whether or not the brand knows it.
You can outsource roaming. You shouldn’t outsource knowing what it costs you.
