What is a failed-to-deliver SMS?
“Failed to deliver SMS” is a metric that measures how many SMS messages weren’t delivered to your subscribers. The metric is expressed as a percentage of messages that didn’t reach their intended recipients.
“Failed SMS” is more common than a “bounced SMS” because it’s an umbrella term that can cover a variety of reasons why an SMS message didn’t deliver.
Common reasons why an SMS might fail to deliver include:
- Incorrect or invalid phone number: Phone numbers that are either missing digits, not formatted properly, or don’t exist at all can cause SMS delivery failure.
- Carrier restrictions: Some carriers may block certain messages, such as messages from unregistered or unverified numbers, or messages containing S.H.A.F.T content.
- Network issues: Temporary network outages, congestion, or maintenance work may result in failed SMS delivery.
- Spam filters: Spam filters can sometimes classify even legitimate SMS messages as spam by mistake.
Tips to reduce failed SMS delivery
- Track reasons for SMS failure: Use a marketing automation platform to identify why your SMS messages failed to deliver so you can fix the problem.
- Use a two-step opt-in: When someone subscribes to your SMS list, they’ll receive an automated message asking them to reply with a keyword like “YES”. A double opt-in keyword is a great way to confirm that an SMS subscription phone number is valid.
- Keep your SMS lists clean: Maintain a clean list by automatically removing invalid phone numbers or unengaged recipients.
- Avoid sending MMS during holidays: MMS can result in failed sends if networks take too long to deliver messages (usually during busy sending times, like holidays or Black Friday Cyber Monday). Note, however, that this does not apply to US short codes.
Sign up for Klaviyo and use the SMS deliverability hub to make sure your text messages are reaching as many recipients as possible.