SMS Not Sending

If SMS messages in your dunning campaigns are showing a "Failed" status or customers report not receiving them, the issue usually involves phone number formatting, opt-out status, or carrier filtering.

Symptoms

• SMS messages show Failed status in the campaign delivery log
• Customers confirm they did not receive the SMS
• SMS delivery rate is significantly below expectations
• The delivery log shows error codes like UNDELIVERED or INVALID_NUMBER
• SMS credits are not being consumed despite active campaigns

Common Causes

1. Invalid phone number format -- the phone number on file is missing the country code, contains extra characters, or is otherwise malformed
2. Customer has opted out -- the customer previously replied STOP to an SMS, which permanently opts them out of future messages
3. Carrier filtering or blocking -- the mobile carrier flagged the message as spam or blocked it due to content or volume patterns
4. Insufficient SMS credits -- your LostChurn account does not have enough SMS credits to send the message
5. Unsupported destination country -- the customer's phone number belongs to a country that is not enabled in your SMS settings

Step-by-Step Fix

1. Check the SMS delivery log

Navigate to Campaigns > Delivery Logs and filter by Channel: SMS. Look at the Status and Error columns for the specific message:

2. Verify phone number format

LostChurn requires phone numbers in E.164 international format:

+[country code][number]

Examples:

• US: +14155551234
• UK: +447911123456
• DE: +4915112345678

Common formatting issues:

• Missing the + prefix
• Missing the country code (e.g., 4155551234 instead of +14155551234)
• Including spaces, dashes, or parentheses (e.g., (415) 555-1234)
• Using a landline number instead of a mobile number

If the phone number is incorrect, update it in your payment processor. LostChurn syncs customer data from your PSP, so changes made there will be reflected in LostChurn on the next sync.

3. Check the opt-out list

Customers who reply STOP to any SMS from LostChurn are automatically and permanently opted out. This is required by telecommunications regulations (TCPA, GDPR).

To check if a customer has opted out:

1. Go to Settings > SMS > Opt-Out List
2. Search for the customer's phone number
3. If the number appears, the customer has opted out and cannot receive SMS through LostChurn

If a customer has opted out, consider switching their campaign to email-only delivery.

4. Check SMS credits

Go to Settings > Billing > SMS Credits to view your current balance. If the balance is zero, SMS messages will fail with INSUFFICIENT_CREDITS.

SMS credits are consumed per message segment. Standard messages (up to 160 characters) use 1 credit. Longer messages are split into multiple segments:

To add credits, click Buy Credits on the billing page or enable Auto-refill to automatically purchase credits when your balance drops below a threshold.

5. Enable destination countries

By default, LostChurn enables SMS to the United States and Canada. If your customers are in other countries, you need to enable those destinations:

1. Go to Settings > SMS > Enabled Countries
2. Search for and enable the countries where your customers are located
3. Click Save

6. Review message content

Some carriers filter messages that contain certain patterns:

• Shortened URLs (use full URLs or your custom branded domain instead)
• ALL CAPS text
• Excessive punctuation or special characters
• Missing opt-out instructions (LostChurn appends "Reply STOP to unsubscribe" automatically)

Review your campaign SMS templates in Campaigns > [Campaign Name] > SMS Steps and remove any content that may trigger carrier filters.

Still Not Working?

If SMS messages continue to fail after completing the steps above:

1. Check status.lostchurn.com for any incidents affecting SMS delivery.
2. Try sending a test SMS from the campaign editor to your own phone number to verify the SMS pipeline is working.
3. Contact support at support@lostchurn.com with the phone number, campaign name, and error codes from the delivery log. The support team can check delivery status with the carrier.