What is SMS filtering?

SMS filtering is the process carriers use to block or restrict messages that look risky, spam-like, or non-compliant before they reach recipients.

Why filtering exists

• To protect mobile subscribers from spam, fraud, and abusive content.

• To enforce carrier, regional, and regulatory messaging rules.

• To reduce unwanted or unsafe messaging traffic.

How filtering works

Filtering varies by carrier and region. Some filters use basic keyword blocks, while others evaluate patterns such as message frequency, repeated content, opt-in quality, risky terms, or sending behavior.

How to reduce filtering risk

• Send only to contacts who clearly opted in.

• Provide clear opt-out instructions when sending campaign messages.

• Personalize messages with relevant context.

• Avoid restricted topics, excessive punctuation, and spam-like language.

• Keep messages concise.

• Do not repeatedly resend blocked messages.

• Maintain compliant opt-in language and policies where contacts sign up.

How to tell if filtering may be happening

• Messages may show an Undelivered status.

• Some carriers may not report filtering clearly.

• Engagement may drop even when some messages appear delivered.

Troubleshooting

• If messages are repeatedly undelivered, rewrite the content and remove high-risk terms.

• If filtering appears incorrect, collect affected conversation examples and contact Whippy Support.

• If filtered messages are billed, review sending practices to reduce future filtering.