Twilio trial SMS fails with 21606: use the test credentials, not the dashboard ones

On a Twilio trial, do not use the Account SID and AuthToken from the console dashboard to test SMS. Use the test Account SID and test AuthToken under Phone Number, Tools, Test Credentials; those are bound to magic test numbers like +15005550006 that accept fake sends. The dashboard credentials only send from numbers you have actually bought, which is why the From number comes back as invalid.

Context: Stack Overflow #28008938 (accepted answer): A user on a free Twilio trial tries to send SMS with the trial Account SID and AuthToken from the console dashboard and gets error 21606, "The From phone number is not a valid, SMS-capable inbound phone number for your account." The fix is to use the TEST Account SID and TEST AuthToken found under Phone Number, Tools, Test Credentials instead. Those test credentials are bound to Twilio's magic test numbers such as +15005550006, while the dashboard credentials only work after buying a real number.

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Source: Published skill Original query: "Twilio trial SMS fails with 21606: use the test credentials, not the dashboard ones" Key terms: 21606, credentials, dashboard, fails, ones, test, trial, twilio