Improve SMS Deliverability: The Marketer’s Guide to 95% Deliverability Rates

As a marketer, by this time, you would’ve come across the 98% open rates and 35% CTR in SMS marketing. But what happens when your SMS isn’t delivered in the first place? – Wasted marketing spend.

Improving your SMS deliverability is the only way to translate these open rates and CTR to ROI and conversions.

To improve your SMS delivery rate, in this article, we have shared:

• What is the SMS delivery rate
• How to improve SMS deliverability.
• Must follow US and Carrier guidelines for SMS marketing
• Best practices to send SMS in US

What is SMS Deliverability?

SMS deliverability is a metric that refers to the percentage of the SMS texts you’ve sent that have successfully reached your recipient’s message box.

SMS deliverability = (Total number of SMS delivered / Total number of SMS sent ) x 100

How to improve SMS deliverability?

Your SMS providers alone cannot guarantee all your SMS delivery. Moreover, most issues regarding the SMS delivery occur on the recipient’s or Carrier’s end.

Knowing what causes the issues while delivering text messages is the first step in increasing SMS deliverability.

Here are the top 6 reasons why your SMS may not be delivered and how to fix them:

• Invalid Phone Numbers: List Hygiene & Validation
• Consent Violations & Opt-Out Management
• URL/Link Related Filtering: Branded Links & Landing Page Cleanliness
• High Volume & Frequency Abuse
• Using Gray Routes: Reputable SMS Provider with Direct Carrier Connections
• Your Message is Too Long: Limit message to 160 characters

1. Invalid Phone Numbers: List Hygiene & Validation

One of the major reasons for failed delivery is incorrect phone numbers. Sending messages to numbers that are mistyped, or belonging to a landline, will never reach the message box.

Keep an eye out for typing/ formatting errors, and spam numbers too.

How to fix: Maintain Your List Hygiene

• Validate the phone numbers when your customers sign up. You can enable double opt-in and validation options in your form. This way, you can ensure only correct phone numbers are added to your list.
  • Format: Is it a correctly formatted US number?
  • Type: Is it a mobile or landline?
  • Validity/Reachability: Is it an active, reachable number?
  • Carrier: Which carrier is it associated with?
• Even with validation and double opt-in, lists can degrade over time as numbers change or become inactive. Use list management platforms to automatically remove hard bounces and add them to a suppression list.
• If you have automated processes, consider a deeper, periodic (e.g., quarterly) bulk validation of your entire SMS list.
• Segment your contacts who consistently fail to receive messages, or who haven’t engaged. You can then exclude these segments from SMS campaigns to maintain a high delivery rate. Re-engage them with other channels like Win back emails or retargeted ads.

2. Consent Violations & Opt-Out Management

SMS marketing is permission-based. If you’re sending texts without proper consent, you are violating regulations like TCPA and CTIA in the U.S. In addition to that, carriers are also likely to flag and block your messages.

How to fix: Implement Strong Consent & Opt-Out Flows

• Use double opt-in: After the initial signup, send a confirmation SMS asking the user to reply “YES” to receive texts. This ensures they genuinely want your messages and builds carrier trust.
• Disclose intent clearly: On your signup forms or popups, state what kind of SMS you’ll send (e.g., offers, order updates), how often, and include a link to your privacy policy.
• Automate opt-out management: Every message should include an opt-out instruction (e.g., “Reply STOP to unsubscribe”). If a user opts out, they must be immediately added to a suppression list.
• Monitor spam complaints: If users report your number as spam, carriers can throttle or block your messages. Use analytics tools to identify which messages trigger complaints and adjust accordingly.
• Stay compliant with carrier & legal guidelines: Follow rules from the TCPA, CTIA, and specific mobile carriers. This includes sending texts only during permissible hours and avoiding prohibited content types.

3. URL/Link Related Filtering: Branded Links & Landing Page Cleanliness

If your SMS contains links, carriers scrutinize them closely. Ensure your links don’t look spammy and do not redirect multiple times.

How to fix: Use Branded, Clean, and Trustworthy URLs

• Avoid public URL shorteners: Links like bit.ly or tinyurl are commonly abused by spammers. Carriers often block messages containing these
• Use your domain or a dedicated subdomain: A custom domain (or subdomain) that aligns with your brand boosts deliverability and builds user confidence when they click.
• Limit redirects: Multiple redirects or cloaked URLs can trigger spam filters. Ensure your link leads directly to the landing page with minimal hops.
• Landing page cleanliness matters: Carriers check not just the link but the content on the destination page. If your landing page is filled with spammy elements, it may affect future deliverability.
• Use HTTPS links only: Secure links improve both deliverability and user trust. Avoid sending HTTP links altogether.
• Avoid overloaded messages: SMS with multiple links or excessive characters may appear suspicious. Stick to one strong CTA link per message.
• Run regular audits of the SMS links you send. Use tools like Google Safe Browsing and SMS testing platforms to identify potential delivery issues before launching campaigns.

4. High Volume & Frequency Abuse

Sending a large volume of SMS messages frequently in a short period can trigger carrier-level filtering. This often leads to spam complaints or opt-outs.

How to fix: Control Volume, Pace, and Frequency

• Warm up your SMS sending: If you’ve just started SMS campaigns or ramped up your list size, don’t blast thousands of messages at once. Gradually increase your sending volume to build trust with carriers.
• Respect frequency limits per user: No one wants five texts a day. Excessive texting leads to user fatigue, higher unsubscribe rates, and possible carrier flags. Follow a best-practice frequency of 2 to 4 texts per month unless customers have explicitly opted in for more.
• Segment and prioritize: Avoid sending to your entire list. Send messages to smaller, high-intent segments based on behavior (e.g., cart abandoners, recent buyers). This keeps volume down and relevance high.
• Stagger promotional & transactional texts: If you send order confirmations and promotional offers back-to-back, users may feel overwhelmed. Space them out with intent.

5. Using Gray Routes: Reputable SMS Provider with Direct Carrier Connections

This is a critical, often hidden, factor that can harm deliverability and expose your business to risk.

Using gray routes for sending your SMS can lead to:

• Extremely Poor Deliverability: They are prone to severe filtering, blocking, and unpredictable delivery delays by carriers.
• Security Risks: Gray routes are often less secure, making your data potentially vulnerable to interception or manipulation.
• Legal & Compliance Risks: Using gray routes can be illegal or violate carrier terms of service.
• Lack of Visibility: You get very little transparency or reliable delivery reports when using gray routes.

How to fix: Always partner with an SMS service provider that exclusively uses direct, legal connections with mobile carriers.

6. Your Message is Too Long: Limit message to 160 characters

Standard SMS limit = 160 characters (including spaces and punctuation). If you exceed this, your message will be split into multiple parts, which can:

• Increase costs.
• Reduce deliverability.
• Break the message mid-sentence (depending on the carrier or device).

How to fix:

• Edit your message to be under 160 characters.
• Use link shorteners (preferably branded) to reduce URL length.
• Remove redundant words or punctuation.
• Consider sending a short teaser via SMS and linking to full content.

US and Carrier guidelines for SMS marketing

Sticking to US guidelines is not just a best practice, it’s a must do in SMS marketing. In this section we’ve covered a basic overview of TCPA, CTIA and A2P 10DLC that are essential to improve SMS deliverability.

It’s only for education purposes and SHOULD NOT be considered as legal advice.

1. TCPA (Telephone Consumer Protection Act)

The TCPA is a law that governs telemarketing calls, and text messages. Its primary goal is to protect consumers from unwanted automated communications.

Key Requirements for SMS under TCPA:

• Express Written Consent (for Marketing Messages): Before sending any marketing or promotional SMS messages, you must obtain “prior express written consent” from the recipient. You can obtain consent using a keyword opt-in option.
• DO NOT USE SHAFT CONTENT (sex, hate, alcohol, firearms, or tobacco)
• Transactional vs. Promotional Messages: The TCPA distinguishes between promotional and transactional messages, impacting consent requirements. Never embed promotional content within a transactional message unless you have explicit marketing consent for that user.
• Mandatory Opt-Out Process: Consumers must have a clear, free, and easy way to revoke consent at any time. Opt-out requests should be processed immediately or within 24 hours.
• Quiet Hours: The TCPA restricts sending times to protect consumers from disturbances.

2. CTIA Guidelines (Cellular Telecommunications Industry Association)

Carriers will filter and block messages that violate CTIA guidelines. It can severely impact your SMS deliverability so following the CTIA guidelines is not optional, it’s a must.

Core CTIA Principles:

• Consent, Clarity, Control: These three Cs underpin all CTIA guidelines.
  • Consent: Requirement for clear, express consent.
  • Clarity: Messages must be transparent about who is sending them, what the purpose is, and what to expect.
  • Control: Users must have an easy and prominent way to opt out.
• Clear Disclosure in Opt-in: Beyond TCPA, CTIA emphasizes the clarity of your opt-in message. It should include:
  • Purpose of the messages (e.g., “marketing alerts,” “order updates”).
  • Message frequency (e.g., “approx. 4 msgs/month”).
  • “Message and data rates may apply.”
  • Link to your Terms & Conditions and Privacy Policy.
  • Clear opt-out instructions (e.g., “Text STOP to cancel”).
• Brand Identification: Every message should clearly identify your brand, either in the sender ID or the message body itself.
• Timely Opt-Out Processing: CTIA reinforces the immediate honoring of opt-out requests.
• No List Sharing/Selling: Consent is specific to your brand and campaign. You cannot buy, sell, or transfer opted-in lists.

3. A2P 10DLC

It enforces many of the TCPA and CTIA principles. This framework applies to businesses that send SMS over standard 10-digit phone numbers in the U.S. It’s how carriers know you’re a legitimate sender and not a spammer.

You just need to register your business with The Campaign Registry (TCR) through your SMS provider.Then, register a campaign for each type of message you plan to send.

For Campaign registration you’ll need :

• Use Case: Select the specific purpose (e.g., Marketing, Transactional, Two-Factor Authentication, Customer Service, Mixed).
• Sample Messages: Provide 3-5 realistic examples of messages you will send for that campaign type. These examples help carriers understand your content.
• Opt-in Flow: Describe how users opt-in to your messages (e.g., “Web form with checkbox,” “Keyword opt-in”).
• Message Frequency: Indicate how often messages will be sent.

5 Best Practices For High Performing SMS Campaigns

Once you’ve made a solid deliverability, these best practices will help you to maximize your SMS campaign’s ROI.

Here are the 5 best practices to improve your SMS campaigns:

• Craft Compelling & Compliant Content: Keep your message clear, concise, engaging and compliant to US regulations (TCPA, CTIA)
• Strategic Opt-In & Opt-Out Flows: Always get explicit permission before sending texts, and make opt-out options easy, visible, and immediate.
• Audience Segmentation & Personalization: Segment your contacts based on behavior, preferences, or location, to personalize your texts.
• Optimal Sending Times & Frequency: Send messages at the right time of day when your audience is most likely to engage, without overwhelming them with too many texts.
• Leverage Two-Way Messaging: Allow customers to reply to your messages to ask questions, or confirm appointments. This way you can build better engagement and trust.

Wrapping Up!

SMS marketing is one of the most effective marketing channels with 7000% ROI. The challenge is : Sending SMS does not mean that the messages are delivered.

You can overcome it by following the US regulations and best practices. It may seem overwhelming and a lot of work, but with Omnichannel tools like Retainful you can easily improve SMS deliverability.

Also Read:

• Email Deliverability – How to Improve It in 2025?
• Real-World Omnichannel Marketing Guide for Growing Marketers

Frequently Asked Questions