How to monitor and maximize SMS/MMS deliverability

SMS/MMS messaging is a powerful tool for reaching your customers in real-time, whether you're deploying time-sensitive order updates, extending exclusive offers, or offering conversational support. However, sending the message is just the first step. If your messages don’t get delivered, even the best offers or urgent alerts won’t have an impact.

Some factors affecting deliverability are outside our control, but there are proactive steps you can take to maximize your SMS/MMS campaign success. This guide will walk you through proven strategies to optimize messaging, troubleshoot common delivery issues, and leverage powerful tools like FreeClimb Messaging API to boost message success and enhance customer engagement.

What is SMS deliverability and why is it important?

SMS deliverability refers to the percentage of messages that successfully reach recipients’ mobile devices. Monitoring your delivery rate is key for diagnosing performance issues, whether they’re technical like latency or related to your campaign strategy, such as audience targeting or message content. 

A low delivery rate often signals problems with your contact list, carrier, or message formatting. On the other hand, if delivery rate is high but engagement is low, the issue could lie in timing, message clarity, or the strength of your call to action.

For security-sensitive use cases like two-factor authentication (2FA), tracking successful logins and resend requests provides deeper insight into deliverability. And when using two-way messaging, monitoring reply rates can reveal valuable information about customer engagement.

Why your SMS messages aren’t getting delivered (and how to fix it)

Below are some of the most common causes of undelivered SMS messages and practical solutions to resolve them.

1. You have not registered your SMS/MMS traffic 

In the U.S., carriers require all Application-to-Person (A2P) or business-to-consumer messaging traffic to be registered. Failure to register results in your messages not being sent or blocked as spam. If you are sending SMS/MMS messagings via a 10-digit long code (10DLC) phone number, that traffic must be registered with The Campaign Registry. 

How to address this:

Leverage FreeClimb’s concierge service to navigate 10DLC, toll-free, and short code registration processes, helping you to deploy your campaigns faster.

2. Messaging volume exceeds your number type limit

Each number type – long codes (10DLC), toll-free numbers, short codes – has specific messaging throughput limits. When you exceed your number type rate limit, your messages may get flagged as spam by carrier filters. 

‍Learn more about each number type, their use cases, and associated registration fees.

3. Spam filters blocked your message

Carriers use spam filters to protect users from unwanted or fraudulent messages. If your SMS content includes suspicious keywords, repeated phrases, or follows aggressive sending patterns, it may be flagged and blocked. 

How to address this:

• Always include a clear opt-out option 
• Send personalized, relevant content instead of bulk or generic promotions
• Make sure your campaigns comply with TCPA guidelines

4. Invalid phone number or device issues

SMS delivery failures can occur if the recipient’s phone number is incorrectly formatted, unassigned, disconnected, or no longer in service. Even with a valid number, technical issues on the recipient’s device — such as low storage, software glitches, or carrier restrictions — can block message delivery. Some users may also have device settings that intentionally block SMS, adding another layer of complexity. 

How to address this:

• Regularly clean and validate your contact lists to remove invalid or outdated numbers
• Purchase validated phone numbers using FreeClimb API
• For sensitive transactions, consider multi-factor validation to verify user identity across multiple channels

5. Carrier service disruptions

Occasionally, SMS delivery fails due to carrier service disruptions, such as network maintenance, technical glitches, or outages. These disruptions can block message delivery even when your system is working properly. 

How to address this:

• Monitor carrier service status for updates on outages
• Retry sending messages once the issue is resolved
• Use a messaging platform with high availability and built-in fault tolerance to minimize the impact of carrier disruptions

Monitoring SMS deliverability made easy with FreeClimb API

With so many factors affecting deliverability, you need full visibility and control over your messages. Built on an enterprise-grade, fault-tolerant platform, FreeClimb API ensures your messages make it through with low latency, even during outages. With detailed logging and debugging tools, you’ll always know when messages are delivered or need attention. Plus, you can easily automate responses to opt-ins, opt-outs, and “help” keywords to keep your lists updated and compliant with carrier regulations.

Ready to boost your deliverability? Sign up for free, grab a virtual number, and start sending test messages with complimentary credits today.