Why are my Texts not Sending? Common Causes and Tips

1. Improper number registration

Mobile carriers require business phone numbers to be registered before texting customers. In the U.S., 10-digit local numbers (10DLC) must be registered with The Campaign Registry, while toll-free numbers need registration through service providers like Plivo or Twilio. Unregistered numbers may experience message filtering or blocking by carriers.

2. Content flagged by carrier filters

Carriers employ sophisticated filters to block messages containing potentially problematic content. These filters help protect consumers from spam, fraud, and inappropriate material. Here's a breakdown of what typically gets flagged:

• SHAFT content (sex, hate, alcohol, firearms, tobacco)
• Other prohibited topics (profanity, cannabis, high-risk financial services)
• Suspicious links or link shorteners
• Excessive spelling/grammatical errors

3. Sending patterns triggering filters

Carrier filters are designed to detect and prevent spam-like behavior in SMS messaging. Certain sending patterns can trigger these filters, potentially leading to blocked messages or penalties for the sender. 

• Repetitive messaging: Sending identical or very similar messages repeatedly, especially without receiving replies, can be flagged as potential spam.
• High-volume sending: Dispatching a large number of messages in a short time frame can overwhelm carrier systems and trigger spam filters.
• Frequency considerations: While there's no universal rule for daily text limits, carriers monitor the frequency of messages from individual senders.
• Time-based patterns: Sending messages at odd hours or in rapid succession can raise red flags with carrier filtering systems.
• Lack of engagement: A low response rate or high number of opt-outs can indicate to carriers that messages may be unwanted.

4. International messaging complexities

International messaging complexities present significant challenges for businesses engaging in cross-border SMS communications.

Regulatory Variations:

• Country-specific rules: Each nation has its own set of regulations governing SMS marketing and business communications.
• Consent requirements: Opt-in procedures and consent management vary widely between jurisdictions.
• Content restrictions: Some countries have stricter content guidelines than others, particularly for sensitive topics.

Examples of country-specific regulations:

• Canada: Canadian numbers can only be texted using toll-free numbers for business communications.
• European Union: GDPR imposes strict data protection and consent requirements for messaging.
• China: All SMS content must be pre-approved by Chinese authorities before sending.
• Australia: The Spam Act 2003 requires explicit consent and easy opt-out methods for commercial messages.

Technical considerations:

• Number formatting: Different countries use various formats for phone numbers, which can affect message routing.
• Character encoding: Some languages require specific character sets, impacting message length and delivery.
• Time zones: Sending times must be carefully managed to comply with local regulations on acceptable hours for business communications.

5. Technical issues

Hardware problems with carriers or service disruptions with SMS providers can significantly impact message delivery. Here are some carrier infrastructure issues:

• Network outages: Carriers may experience temporary or prolonged outages due to equipment failures, power issues, or natural disasters. During these periods, SMS messages cannot be routed through the affected areas.
• Capacity overload: During high-traffic periods (e.g., holidays, major events), carrier networks may become congested, leading to delayed or failed message deliveries.
• Hardware failures: Critical components like SMS centers (SMSCs) or routing equipment may malfunction, disrupting the flow of messages.
• Maintenance windows: Scheduled maintenance on carrier networks can temporarily halt or slow down message processing.

SMS provider service disruptions:

• API outages: If an SMS provider's API experiences downtime, messages sent through that service will fail to be delivered.
• Server issues: Problems with an SMS provider's servers (e.g., database failures, software bugs) can prevent message processing and delivery.
• Routing problems: Issues with message routing algorithms or connectivity between the provider and carriers can cause delivery failures.
• Third-party dependencies: SMS providers often rely on multiple carriers and other services. Issues with these dependencies can cascade into delivery problems.

6. Recipient-side issues

Recipient-side issues can significantly impact SMS delivery success. 

Invalid or deactivated phone numbers:

• Numbers change or become inactive over time
• Typos in database entries lead to non-existent numbers
• Temporary deactivations during number porting processes

Landlines without SMS support:

• Many traditional landlines can't receive text messages
• Some VoIP services may not support SMS
• Business phone systems often lack SMS capabilities

Unsubscribed contacts:

• Users who have opted out cannot be messaged legally
• Unsubscribe requests must be honored promptly
• Some users may report messages as spam even after opting in

Phone settings filtering unknown senders:

• iOS and Android offer built-in spam filtering features
• Third-party apps can block messages from unknown numbers
• Carrier-level filtering may quarantine messages from unfamiliar senders

1. Choose the right service provider

A reliable texting service provider plays a critical role in ensuring seamless SMS delivery. Look for providers that:

• Offer excellent customer support.
• Assist with phone number registration to meet regulatory standards.
• Have strong user reviews on platforms like G2 and Trustpilot.

2. Adhere to compliance rules

Regulatory compliance is essential in the texting industry. To avoid carrier filtering or blocked messages:

• Ensure your texting number is properly registered.
• Collect explicit SMS opt-ins from recipients.
• Familiarize yourself with industry-specific guidelines and follow them diligently.

3. Optimize your message content

Carrier filtering often targets messages with inappropriate or questionable content. To stay compliant:

• Avoid using profanity or prohibited topics.
• Keep your messages professional and concise.
• Proofread carefully before sending.

Well-crafted, thoughtful content helps ensure that your texts bypass filters and reach recipients.

4. Mind your timing and frequency

When and how often you send messages can impact delivery rates. To optimize timing:

• Schedule marketing messages during business hours.
• Limit the frequency of texts to avoid overwhelming recipients and triggering carrier blocks.

5. Maintain a clean contact list

Maintain up-to-date SMS contact lists by:

• Removing unsubscribed contacts
• Eliminating invalid numbers
• Updating contact information as needed

6. Monitor and track performance

Many SMS platforms provide analytics on message delivery rates. Use these tools to:

• Identify trends or issues in message failures.
• Remove problematic contacts or adjust your strategy based on insights.

These practices can help you minimize delivery issues and maintain effective communication with your audience.

While implementing these best practices can significantly improve your SMS delivery rates, partnering with a robust SMS API platform like Plivo can provide additional tools and support to address text delivery issues more comprehensively.

1. Programmatically send and receive text messages

With Plivo's SMS API, businesses can programmatically send and receive text messages, enabling global customer interaction at scale. Whether you're using SMS for customer support, marketing campaigns, or transactional messages, Plivo's reliable API ensures your messages reach recipients quickly and efficiently.

2. Enable your applications with SMS in minutes

Plivo makes it easy to integrate SMS capabilities into your applications. Whether you're sending confirmation texts, alerts, or reminders, you can enable SMS functionality in just a few minutes, ensuring your messaging service is up and running without delay.

3. Two-Factor authentication (2FA)

Plivo's platform supports Two-Factor Authentication, enhancing the security of your applications by sending dynamic verification codes. This is essential for businesses that need to secure user accounts and protect sensitive information at scale.

4. Alerts and Notifications

Plivo’s SMS API allows you to send automated alerts, notifications, and reminders to your customers. Whether you're notifying users of account changes, shipping updates, or system maintenance, Plivo ensures your messages are delivered reliably, even at high volumes.

5. SMS autoresponder

Plivo’s SMS Autoresponder feature ensures that your customers receive prompt responses, even when you’re away. Automate responses to common queries or set up out-of-office replies, providing a seamless customer experience.

6. Great delivery even at high scale

Plivo ensures excellent message delivery rates, even when sending high volumes of messages. With features like smart queueing for carrier compliance and local connect for higher open rates, your messages will reach their intended recipients with consistency.

With Plivo's SMS API, you can improve SMS delivery and create an efficient, scalable messaging system for your business. Whether you're handling customer communication or running marketing campaigns, Plivo provides the tools you need to send messages reliably and securely. Learn more about Plivo’s solutions here.