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Free SMS Spam Checker

Paste a text to see which words US carriers filter, how to fix each one, and a cleaner version to copy.

SMS Spam Checker illustration

Problem words get marked in your text as you type.

Carriers filter texts silently, and no dashboard shows it.

When a carrier filters your text, you usually don't get an error. The dashboard says “sent,” the recipient gets nothing, and your reply rates quietly crater. Carriers do this by scoring every message against patterns learned from billions of scam texts, which means legitimate businesses get caught for sounding like scams, not for being one. Inside VoiceDrop, the same checker also learns from each account's own delivery history.

Some offers are restricted whatever the wording.

Carriers judge these by what the text offers, so no rewrite fixes them.

  • Debt relief or credit repair. Carriers ban debt relief offers. Rewording won't get them through.
  • Loan or credit offer. Only the lender itself can text loan offers, on a registered direct-lending campaign.
  • Cannabis or CBD. Banned on every US number, even in states where it's legal.
  • Gambling or sweepstakes. Most carriers refuse betting offers. Sweepstakes need an approved short code.
  • Income or investment pitch. Carriers ban income and investment promises. Take the claim out.
  • Prescription drugs. Drug offers are banned. Take the drug name and the offer out.
  • Tobacco, vaping or firearms. Age-restricted, and many providers refuse it. Ask yours before sending.
  • Alcohol. Allowed only to people who gave a birth date when they signed up.

Source: CTIA Messaging Principles.

SMS deliverability stands on three legs.

  1. Registration. US business texting runs on A2P 10DLC: your brand and campaign get vetted and registered with The Campaign Registry. Unregistered traffic is throttled or blocked outright, regardless of copy.
  2. Copy. This is the leg the tool checks: the wording patterns spam models score. Write like a person texting a person: name yourself, say why you're texting, one clear ask, full URLs, and an opt-out.
  3. Behavior and list quality. Sudden volume spikes, high invalid-number rates, and missing opt-out honoring all burn sender reputation. Clean your list first; the phone number formatter catches dead and duplicate numbers before they hurt you.
FAQ

Here are answers to 7 questions about why texts don't get delivered.

The most common causes, roughly in order: your number or brand isn't registered for A2P 10DLC (US business texting registration), your copy matches spam patterns and gets filtered by carrier machine-learning, you're sending too fast for your number type, or the destination numbers are landlines. Filtering is usually silent: the message shows as sent, but never arrives.

US carriers run every business text through spam-detection systems before delivery. Messages that pattern-match known scam framing (prize language, urgency stacking, link shorteners, brand impersonation) are dropped or blocked, often without any error back to the sender. It's the SMS equivalent of an email spam folder, except the message just disappears.

No single word is fatal on its own; filters score patterns. The reliable offenders are prize wording ("winner", "guaranteed", "claim your"), pressure stacking ("act now", "final notice", "expires today"), piled-up free offers ("100% free", "free gift"), runs of capital letters, and public link shorteners like bit.ly. The checker above marks each one in your text, says why carriers filter it, and gives the fix.

Mostly no, and wording doesn't change it. Carriers judge these by what the text offers. Debt relief, credit repair, cannabis and CBD are banned on business numbers, and most messaging providers refuse gambling too. Loans are allowed only from the lender itself, on a campaign registered as direct lending. Alcohol needs an age gate at sign-up. The checker flags each of these as a restricted category and says what is allowed.

Yes. Under the list of problems there is a cleaner version with the pressure words cut, capitals and exclamation marks put back to normal, short links swapped for a placeholder, and the text trimmed toward one segment. It is made by fixed rules in your browser, so your text is never uploaded.

Yes. Multi-segment messages correlate with higher filtering rates and cost more per recipient. Keeping copy inside one 160-character GSM-7 segment is both the cheapest and the safest configuration. The character counter tool can show you what's pushing you over.

Copy is only one of three deliverability legs. The other two are registration (A2P 10DLC brand and campaign vetting for US traffic) and sending behavior (volume ramp, opt-out handling, reply rates). A clean message from an unregistered number still gets filtered. If registration and copy are both solid, look at list quality: dead numbers and landlines drag down your sender reputation.

Want deliverability handled for you?

VoiceDrop registers your traffic, screens copy against live rejection data from your own sends, rotates message variations automatically, and pairs SMS with ringless voicemail in your own voice.

See Bulk SMS MarketingBook a Demo
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