How Does SMS Delivery Work

When an SMS is sent from the Topline OS platform, it goes through various steps that can be illustrated as follows:

As you may have noticed, an SMS that you send to a contact goes through multiple layers. If there is a failed sending or delivery, it could indicate an error or filter at any of the mentioned layers.

Where can I find Sending/Delivery Errors in Topline OS?

In most cases, when an SMS fails to send or deliver, we display an error in the conversation view that appears like this:

The error message and error code will provide you with clues about what is going wrong and how to proceed from there.

Possible Reasons for Failure Include:

At the Topline OS layer:

1. DND is Enabled

When DND is enabled for a contact on the SMS channel or overall, Topline OS doesn't send the SMS and displays an error in the conversation screen.

2. Number is a Landline Number (Number Validation)

When number validation is enabled, Topline OS checks if the contact's phone number is SMS-capable before attempting to send the SMS. If the number is not SMS-capable, Topline OS skips sending the SMS and shows an error in the conversations screen.

3. Account is New and Undergoing Ramped Sending

For newly created accounts, Topline OS gradually increases the sending limits to prevent spamming or phishing.

4. Account has Exhausted the Daily Quota Set

Set a daily limit on SMS sending for each account. When the limit is reached, Topline OS skips sending SMS in bulk actions and automations. However, 1:1 SMS messages are still sent to allow clients to reply to their leads.

5. Account SMS Sending Privileges Have Been Suspended Due to a High Error Rate, Opt-out Rate, or Carrier Complaint Rate

Topline OS monitors error rates, opt-out rates, and carrier complaint rates for all accounts to prevent spamming and phishing. If any of these thresholds are exceeded, SMS sending privileges for the account are suspended for a certain period. Any attempted SMS sending during this time will be skipped, and an error message will be displayed on the conversation screen.

At Sender Carrier Network Layer

1. 30003 - Unreachable Destination Handset

• The destination handset you are trying to reach is switched off or otherwise unavailable.

• The device you are trying to reach does not have sufficient signal

• The device cannot receive SMS (for example, the phone number belongs to a landline)

• There is an issue with the mobile carrier

2. 30004 - Message Blocked

• The destination number you are trying to reach is blocked from receiving this message.

• The device you are trying to reach does not have sufficient signal.

• The device cannot receive SMS (for example, the phone number belongs to a landline).

• The destination number is on India's national Do Not Call registry.

• There is an issue with the mobile carrier.

• You have sent a message from a US/CA Toll-free number to an end user handset that has previously responded with "STOP" or another opt-out keyword.

3. Size Limit of an Attachment to an SMS or an Email

4. Geo Permission Issues for International SMS

5. The Body Exceeds the Limit of 1600 Characters

• If you are using a trigger to send SMS. Check the body of the message. Also, check to see if there is a custom value of {{message.body}}
  

  • For example, if someone replies via email and their email exceed the limit of 1600 characters, the message will not send if you have the custom value {{message.body}}
    

    

    
    FAQ's

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

    A. Charges will apply to SMS messages where delivery was attempted.