A fake DLR is a delivery report that says "delivered" when the message never reached the handset, because an intermediate platform generated it instead of passing on the operator's real report. You detect it by comparing DLRs with real handset tests, by watching for reports that arrive too fast or too uniformly, and by checking conversion on OTP traffic.
How delivery reports should work
When you submit a message over SMPP with registered delivery requested, the operator's SMSC tries to deliver it and then sends back a receipt with a final status such as DELIVRD, UNDELIV or EXPIRED. Each provider in the chain should pass that receipt back unchanged, mapped to your message ID. The statuses are explained in SMS delivery report statuses.
A fake DLR breaks this chain: some platform in the middle creates its own "DELIVRD" receipt without real confirmation from the operator.
Why fake DLRs happen
- Grey or cheap routes where messages are dropped, delayed or sent through channels that return no receipt. Generating "delivered" hides the problem and keeps the customer paying. See grey SMS routes.
- Billing on delivered messages: if the supplier is paid only for delivered messages, a fake report inflates revenue.
- Platform defaults: some systems return DELIVRD when the upstream supplier does not support DLRs at all. This is not always fraud, but the result for you is the same: you cannot trust the number.
- Message dropping: a reseller may discard part of the traffic and report it as delivered.
Warning signs
| Sign | What it suggests |
|---|---|
| Delivery rate of 99 to 100% on a destination where other routes show 85 to 95% | Reports are not reflecting reality: some numbers are always off, ported or invalid |
| DLRs arrive within a second of submission, always | Generated by the platform, not after a real delivery attempt |
| Identical "done date" and "submit date" on every receipt | Receipt created at submission time |
| Invalid or unallocated numbers come back DELIVRD | Strong indication of fake reports |
| Error code always 000, even on failures | The platform does not pass operator errors |
| OTP conversion drops while delivery rate stays high | Users are not receiving the codes |
How to test for fake DLRs
- Handset tests: send to real SIM cards on each network in the destination country, either your own or a test panel service. Compare what the phone received with what the DLR says. The method is in how to test an SMS route.
- Invalid number test: send a few messages to numbers you know are not allocated or are switched off for a long period. A real route returns UNDELIV or EXPIRED, possibly after hours. A fake one returns DELIVRD.
- Timing analysis: plot the time between submit_sm_resp and DLR. Real distributions vary; fake ones are flat and very short.
- Conversion tracking: for OTP, compare codes sent with codes entered, per route and per country. A route with high delivery and low conversion is suspicious.
- HLR cross-check: an HLR lookup on a sample of numbers shows which ones are inactive; those should not come back delivered.
What to do if you find them
Share the evidence with the supplier: message IDs, timestamps, handset screenshots. A serious supplier will investigate its own upstream. If billing is per delivered message, ask for a credit on the affected traffic. Move critical traffic such as OTP to a direct route and keep a monitoring process running, because quality can change from week to week. Our guide on SMS delivery rate and latency explains what to track continuously.
Avoiding the problem
Choose suppliers who state where reports come from and who accept testing before traffic starts. VoIPMatcher sources A2P SMS routes from its carriers and manages the route, so you deal with one counterpart when something goes wrong. Request an SMS route and tell us how you measure delivery.
Frequently asked questions
Why does my SMS show delivered but was not received?
Either the delivery report is wrong or the problem is on the handset. A route may return a fake DELIVRD status generated by an intermediate platform, or the phone may have received the message but filtered it as spam. Test the same message on real handsets on each network and compare what arrives with the reports.
Is a fake DLR fraud?
Not always, but the effect is the same. Some platforms return DELIVRD by default when their upstream supplier sends no receipts. Others generate delivered statuses on purpose to hide dropped or grey traffic, or to bill on delivered messages. Either way you cannot trust the delivery rate, so treat the route as unreliable until tested.
What SMS delivery rate is suspicious?
A delivery rate of 99 to 100 percent on a destination where other routes show 85 to 95 percent is a warning sign. Every real list contains some inactive, ported or invalid numbers that should fail. Reports that always arrive within a second, with identical submit and done dates, point the same way.
Can I get a refund for fake delivery reports?
If your agreement bills per delivered message, you can ask for a credit on the affected traffic. Share the evidence with the supplier: message IDs, timestamps, handset screenshots and invalid number tests. A serious supplier will investigate its upstream. Without evidence, or after the dispute deadline, a claim is hard to win.
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