Most SMS marketers focus on open rates and click rates. But there's a more fundamental metric that makes those numbers meaningless if it fails: delivery rate. A message that doesn't reach the phone cannot be opened, clicked, or acted on.
Industry-average delivery rates hover around 95–97% for well-managed programs. Brands making the mistakes below routinely see delivery rates drop to 70–80%, silently bleeding campaign performance.
Shared short codes were deprecated by major carriers starting in 2021. If you're still using one, you're sharing a number with potentially hundreds of other businesses — including spammers. One bad actor's behavior affects your delivery. Move to a dedicated short code, toll-free number, or registered 10DLC number.
For businesses using 10-digit long codes in the US, A2P 10DLC registration is mandatory. Unregistered numbers are filtered aggressively by carriers. Registration through The Campaign Registry (TCR) takes 1–2 weeks and is required before sending at scale.
Carriers watch for sudden volume spikes on phone numbers. If a number that typically sends 100 messages per day suddenly sends 50,000, that's a spam signal. Warm up new numbers gradually — start with a few hundred per day and scale over 2–3 weeks.
Certain words and phrases flag automated carrier filtering systems. Common triggers include:
Use natural language. Write like a person, not a flyer.
If your opt-out rate exceeds 1–2% per campaign, carriers notice. High opt-out rates signal that recipients didn't truly consent to your messages — and filtering increases as a result. Opt-outs are a compliance signal, not just a list hygiene issue.
Landlines, VOIP numbers, and disconnected phone numbers generate failed delivery attempts. A high failure rate on a number degrades its reputation. Clean your list every 90 days using a phone number validation service.
Links to domains that look like phishing attempts — misspelled brand names, excessive subdomains, freshly registered domains — will be filtered. Use your actual domain. If you use a link shortener, make sure it's a reputable service or your own branded shortener.
Erratic sending schedules — nothing for 3 months, then 10 messages in a week — look like account compromise to carrier systems. Establish a regular cadence and stick to it.
If your platform doesn't properly handle STOP, QUIT, CANCEL, END, and UNSUBSCRIBE keywords, messages will continue going to people who opted out. This generates spam complaints directly to carriers and can get your number blacklisted.
Most SMS platforms provide delivery receipts and bounce codes. Codes like "30007" (carrier violation) or "30003" (unreachable number) tell you exactly why a message failed. Marketers who ignore these reports miss the chance to fix systemic issues before they compound.
A healthy SMS program looks like:
If you're below these benchmarks, the mistakes above are likely culprits. Fixing them is unglamorous work, but it's the foundation everything else depends on.
Thomas Beck
Digital Marketing Strategist at Textcanon
Helping businesses reach their audience through effective, compliant SMS marketing. Writing about strategy, deliverability, and growth.