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SMS Not Sending / Delivering to Contacts

PostedApril 6, 2025
UpdatedApril 8, 2025
ByMukesh Kumar

Modified on: Tue, 23 Jul, 2024 at 7:44 AM

Troubleshooting SMS delivery failures can be challenging, but this guide will walk you through the potential causes and provide solutions to help resolve any issues. We will cover all possible reasons why an SMS might fail to send or be delivered, along with the necessary troubleshooting steps to ensure successful message delivery.

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How Does SMS Delivery Function?

When an SMS is sent through the VisionaryX platform, it follows a series of steps to ensure successful delivery, which can be outlined as follows:

As you may have observed, an SMS sent to a contact passes through several stages. If there is a failure in sending or delivery, it could point to an issue or filter at any of these stages.

The error message and error code provide valuable insights into the underlying issue and can guide you toward a solution.

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Possible Causes for Failure

At the VisionaryX Layer:

  1. DND (Do Not Disturb) is enabled: When DND is activated for a contact on the SMS channel or overall, VisionaryX will not send the SMS and will display an error in the conversation screen.

    Related help doc: Do Not Disturb (DND) Settings

  2. Number is a landline (Number Validation): When number validation is enabled, VisionaryX checks if the contact’s phone number is capable of receiving SMS. If the number is not SMS-capable, VisionaryX will skip sending the SMS and display an error.

    Related help doc: SMS / Phone Number Validation in VisionaryX

  3. New Sub-Account and Ramped Sending: For newly created sub-accounts, VisionaryX gradually increases the SMS sending limits to avoid spamming or phishing. Agencies have the option to remove these restrictions if desired.

    Related help doc: VisionaryX Phone Messaging Policy (Ramp-Up Model)

  4. Sub-Account Exceeds Daily SMS Quota: Agencies can set a daily limit for SMS sending in each sub-account. Once this limit is reached, VisionaryX will skip sending SMS in bulk actions and automations, but 1:1 SMS messages will still be sent. Agencies control these limits per sub-account.

    Related help doc: VisionaryX Phone Messaging Policy (How to Update Sub-Account Limits)

  5. Suspended Sub-Account Due to High Error/Opt-Out/Complaint Rates: VisionaryX monitors error rates, opt-out rates, and carrier complaints. If any of these thresholds are exceeded, SMS privileges for the sub-account may be suspended temporarily. During this suspension, SMS attempts will be skipped, and an error message will be shown.

    Related help doc: Best Practices for SMS Deliverability and Avoiding SMS Restrictions

At the Twilio/LC Phone Layer:

  1. Number on Twilio’s DND List: If the contact has previously opted out from receiving messages from the Twilio number, the SMS will not be delivered unless the contact re-engages by texting “START” to the Twilio number.

  2. 30001 – Queue Overflow: Twilio queues messages based on the sending rate. If the message stays in the queue for more than 4 hours, it will fail. To reduce this, you can set a shorter validity period within your messaging service settings or API requests.

  3. 30002 – Sub-Account Suspended on Twilio: If your Twilio sub-account is suspended after the message was queued but before delivery, contact Twilio or VisionaryX Support (LC Phone). This failure happens when the account is suspended between message queuing and sending.

At the Sender Carrier Network Layer:

  1. 30003 – Unreachable Destination Handset:

  • The recipient’s phone is turned off or unavailable.
  • The recipient’s phone doesn’t have sufficient signal.
  • The number cannot receive SMS (e.g., a landline number).
  • There is a problem with the mobile carrier.

  1. 30004 – Message Blocked:

  • The recipient’s number is blocked from receiving the message.
  • The recipient’s phone does not have a signal.

Frequently Asked Questions

Why am I being charged for SMS messages that failed to deliver?

Charges will apply to SMS messages where an attempt to deliver the message was made, even if the message ultimately failed to be delivered. This is because the system incurs costs when sending the message, regardless of whether it reaches the intended recipient.

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