Failed SMS

Try it in the demo.

The situation: your app should handle an SMS that cannot be sent (invalid number, opted out) and one that is accepted but never arrives (unreachable handset, carrier filter). On Twilio these are hard to produce on demand.

You need: your app's SMS client pointing at SendMock (http://127.0.0.1:8026 for Twilio SDKs, or the native API). See Connect your app.

StepsCopy Anchor Link

1. Fail at send time. Send from your app to +15005550001. SendMock answers at once with HTTP 400 and Twilio's error JSON, code 21211 (invalid number), exactly as Twilio's test credentials do. Your app should show its error.
2. Fail after sending. Send to +15005550103. The message is accepted, then turns undelivered with 30007 (filtered by the carrier), and your status callback is called with it.
3. Open the conversation in SMS: the failed message shows a red tick with the code on hover; Message details shows the status history and each callback attempt.

Other numbers and codes are on Delivery and test numbers.

With cURLCopy Anchor Link

curl -s http://127.0.0.1:8025/api/v1/sms \
  -H 'content-type: application/json' \
  -d '{"from": "+15550001111", "to": "+15005550001", "body": "Hi"}'
# 400: Rejected with error 21211 (magic number)

In your codeCopy Anchor Link

A test that marks a sent SMS undelivered with Twilio's 30007, so your status callback handler runs. Sending to +15005550103 does the same by itself.

The examples call SendMock's REST API with each language's usual HTTP client and test framework. JavaScript, Go, Java, Rust, Ruby and C# use the small call helper shown under Test helper on their page in Connect your app.

# In your app: text the order update to +8801700000000

sms=$(sendmock sms wait --to +8801700000000 --timeout 10s --json)

failed=$(sendmock sms status "$(jq -r '.id' <<<"$sms")" undelivered --error-code 30007 --json)

jq -e '.status == "undelivered"' <<<"$failed" >/dev/null
jq -e '.error_code == "30007"' <<<"$failed" >/dev/null

What you should seeCopy Anchor Link

The 400 with code 21211 in your app's logs for the first send; for the second, an undelivered message and your callback handler receiving 30007.

Try it in the demoCopy Anchor Link

1. Open Settings > SMS.
2. Type +15005550001 in Test a number: it says "Magic number: Invalid number (21211)".
3. Type +15559990000: a custom rule applies, "Accepted, then undelivered, 30007".

NextCopy Anchor Link

• Advanced: SMS outcome numbers: your own failing numbers.
• Delivery and test numbers