SMS bounce rates measure the percentage of messages that fail to deliver to their intended recipient. High bounce rates waste budget, damage your sender reputation with carriers, and — in worst-case scenarios — trigger spam filtering that affects your entire sending domain. The good news: most SMS bounces are preventable before you send a single message.

What Causes SMS Bounces?

Sending to landline numbers — landlines cannot receive SMS messages. Every message sent to a landline is an immediate hard bounce. In a typical marketing database, 15–25% of numbers may be landlines. Identifying and removing them before sending is the single highest-impact action you can take to reduce bounce rates.

Disconnected numbers — numbers that have been deactivated generate hard bounces. Phone numbers disconnect constantly — people change carriers, cancel plans, or switch devices. A number that was valid six months ago may be completely unreachable today.

Invalid number formats — numbers with incorrect digit counts or non-existent area codes will fail at the network level before even reaching a device.

Full voicemail or blocked numbers — some soft bounces occur when a recipient’s device is off, out of coverage, or has blocked your sender ID. These are harder to predict but represent a smaller portion of overall bounces.

Step 1 — Validate Numbers Before Every Send

Run your contact list through a phone lookup tool before every campaign. Validation confirms which numbers are active and reachable right now — not just at the time they were collected. Remove all Invalid and Inactive numbers from your send list before launching.

For ongoing campaigns, build validation into your data pipeline. Use the Phone Validator API to check numbers at the point of entry so invalid contacts never reach your sending list in the first place.

Step 2 — Filter Out Non-Mobile Numbers

SMS delivery requires a mobile number. Before sending, filter your list to include only numbers where line type is Mobile. Remove Landline, Toll-Free, and review VoIP numbers separately.

Line type data is returned by RealValidito for every number validated. Segment your cleaned list into Mobile-only for SMS campaigns and retain Landline numbers for voice-only outreach.

Step 3 — Suppress VoIP Numbers for High-Volume Campaigns

VoIP numbers can technically receive SMS in many cases, but they carry a higher bounce rate than traditional mobile numbers and are more frequently associated with spam complaints. For large campaigns where deliverability metrics matter, suppressing VoIP numbers reduces bounce rates and protects sender reputation.

Step 4 — Honour Opt-Outs Immediately

Under TCPA regulations, opt-out requests must be honoured within 10 business days. Continuing to send messages to opted-out numbers generates both complaints and bounces. Maintain a real-time suppression list and sync it with your sending platform before every campaign launch.

Step 5 — Scrub Against the DNC Registry

Numbers on the National Do Not Call Registry that receive unsolicited SMS generate complaints that damage your sender reputation with carriers — independently of bounce rates. DNC scrubbing removes these numbers before they cause compliance and deliverability problems simultaneously.

Step 6 — Clean Your List on a Regular Schedule

Phone numbers change status continuously. Numbers that were valid and mobile last quarter may be disconnected or ported to a VoIP carrier today. Build a recurring validation schedule — monthly for active outreach lists, quarterly for dormant databases — to prevent bounce rates from creeping up between campaigns.

What is a Good SMS Bounce Rate?

Industry benchmarks vary by list quality and send volume, but a well-maintained list validated before sending should achieve a bounce rate below 2%. Lists that have not been validated recently often see bounce rates of 10–30%, particularly if they contain large numbers of landline or inactive numbers.

Start with a free list validation on RealValidito — upload your CSV and see exactly how many numbers are invalid, inactive, or non-mobile. Get 1,000 free credits, no card required →