Texts that silently fail are the most common beginner headache — and the cause is almost always one of six things. Work through this list in order; most people find their fix by check 3.

The steps

1. Does the account have a phone number?

   Go to Settings → Phone Numbers. You need a number listed there — texting does not work without one. No number? Click Add Number, pick one in your area code (a few dollars a month), and try again.

2. Is A2P registration approved? (US accounts)

   US carriers require businesses to register before sending texts — it is called A2P. Look under Settings → Phone Numbers for a Trust Center or A2P status. If it says pending or unregistered, that is your answer: texts get blocked or heavily filtered until approval, which can take days. Submit it and wait — there is no workaround.

3. Did the contact opt out?

   Open the contact’s record and check for a DND (“do not disturb”) flag or an SMS opt-out. If someone ever replied STOP, the system correctly refuses to text them. Only the contact can opt back in by texting START.

4. Is the phone number formatted right?

   On the contact record, the number should include the country code — for the US, +1 followed by ten digits. A number saved as “555-0123” with no area code cannot be delivered.

5. Is there credit on the account?

   Texts cost a fraction of a cent each, paid from the account wallet. Check Settings → Billing for the credit balance. Zero balance means silent failures. Turn on auto-recharge so this never happens again.

6. Read the actual error message

   Open Conversations, find the failed message, and hover or click the little red icon next to it. The error code tells you the story — “30007” means carrier filtering (see check 2), “21610” means opt-out (check 3). Search the code plus “Twilio” and you will find the exact meaning.

Common questions

“Everything checks out and it still fails. Now what?” Send a test to a different phone on a different carrier — sometimes one carrier filters and others do not. If that succeeds, it is filtering: soften your message wording (no ALL CAPS, no shortened links) and confirm A2P approval.

“Why do my texts send but get no replies?” That is usually filtering too — your texts land in spam on the recipient side. Registered A2P traffic with normal, personal-sounding wording gets through; blast-style wording does not.

“Do these checks apply outside the US?” Checks 1, 3, 4, 5 and 6 apply everywhere. A2P (check 2) is US-specific, but many countries have their own sender registration rules — the Trust Center screen shows what applies to your region.