TelQ testing platform documentation
TelQ testing platform documentation

Flash call detection

Some suppliers may deliver OTP messages as a flash call instead of an SMS, usually because it is cheaper for them. Your DLR still says "Delivered", but the end user never receives an SMS. Flash call detection shows you when this happens on your routes.

What is a flash call

A flash call is a short call that contains the OTP code hidden in the Caller ID. For example, a call from +44 20 3889 8207 delivers the code 8207. Some apps on the phone can read such codes from the call log automatically.

For OTP traffic, this means the user's app may still work, but the SMS you paid for was never delivered.

How detection works

  1. You send a test through your supplier to one of our flash call-capable test numbers, the same way as any other Live Number Test.

  2. Your supplier does not know it is a test. If it converts SMS to flash calls, it treats the test like any other OTP message and calls our test number.

  3. During the test, our test number listens for incoming calls.

  4. If a call arrives whose Caller ID contains the Test ID Text, the test result is Flash call.

TelQ never places any calls itself. Detection is passive: we only record what your supplier delivers.

Availability

Flash call detection is a paid add-on. It becomes available when your active package includes Flash call. To add it, please contact your account manager.

If your package does not include Flash call, the Flash call destination filter is visible but not active.

Tests that end as Test number offline, Network offline, Internal error or SMPP Connection offline are not billed, the same as other Live Number Tests.

Running a flash call test

  1. In Destinations, click the funnel icon and select Flash call. Only networks with flash call-capable test numbers are shown. These are test numbers that can receive both SMS and calls.

  2. Select the destinations, Sender IDs, texts and suppliers as usual.

  3. Click Run and confirm.

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For flash call tests, some settings are applied automatically. Please carefully read below.

  • Test ID Text is always numeric, with the length you selected. Flash calls can only carry digits, so an Alpha or Alphanumeric Test ID could never be matched. If your Test ID settings are Alpha or Alphanumeric, we switch to Numeric for these tests.

  • TTL is fixed to 3 minutes for incoming call, regardless of your TTL setting. Flash calls arrive within seconds, and keeping the test short reduces the chance of recording an unrelated call.

We recommend using a realistic OTP text, for example "Your verification code is {TEST_ID_TEXT}". Suppliers usually convert only OTP-like messages.

Reading the results

A test delivered as a flash call is shown in the results table as follows:

  • DLR / Rec. Status: the DLR your supplier returned (often "Delivered") and the Flash call receipt status (phone icon).

  • Sender ID: the Caller ID of the incoming call, marked with a phone icon.

  • Text: "—", because no text was received.

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Click the Caller ID to see the Sender ID you sent, the Caller ID received, and the part of the Caller ID that matches the Test ID Text.

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To find flash call results, use the Status filter (Receipt status Flash call) or the Delivered as (channel) filter (Flash call). Both work the same way.

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How the result is decided

What happened during the test

Result

The SMS arrived

Normal SMS result (Positive, Text replaced, etc.). Any later call is ignored.

A call with the Test ID in the Caller ID arrived

Flash call

A call with the Test ID arrived first, then the SMS

Flash call. The SMS that arrived later is ignored.

A call arrived, but its Caller ID does not contain the Test ID

The call is ignored. The result is the same as if no call had arrived.

Nothing arrived within the TTL

Negative

The test number could not start listening for calls

Test number offline, not billed

Limitations

  • The result is a strong indication, not 100% proof. Our test numbers are real phones. A Caller ID containing the Test ID by coincidence is very unlikely, but possible.

  • Coverage is smaller than for SMS tests. Only test numbers that can receive both SMS and calls take part in flash call tests.

  • Voice OTP is not detected. If the code is read out in a voice call, we cannot hear it.

  • Calls via OTT apps (WhatsApp, Viber, Telegram) are not detected. Only regular mobile network calls are recorded.