This section explains how SMS delivery works, the different message statuses that may appear during message processing, and best practices for improving message deliverability.
Understanding Message Statuses
Each SMS message has status values that indicate its progress through the delivery process. SMS delivery status is divided into two stages:
- Sent to Operator Status – Indicates whether the message was successfully processed and submitted by the Unifonic platform.
- Delivered to Customer Status – Indicates the final delivery outcome after the message has been submitted to the mobile operator.
Sent to Operator Status
| Status | Description |
|---|---|
| Sent | The message was successfully submitted to the mobile operator. |
| Not Sent | The message could not be submitted to the mobile operator. |
Delivered to Customer Status
| Status | Description |
|---|---|
| Delivered | Unifonic received confirmation that the message was delivered by the mobile operator or, when available, by the destination device. |
| Undelivered | The message was not delivered to the recipient's mobile device. |
| Pending | The message was submitted successfully, but delivery confirmation or failure information has not yet been received. |
Understanding Undelivered Messages
A message may be marked as Undelivered when:
- The message does not pass platform validations.
- The mobile operator reports that the message could not be delivered to the recipient's device.
Understanding Pending Messages
A message may remain in Pending status when:
- Delivery receipts are blocked or delayed by the mobile operator.
- Temporary network or connectivity issues affect delivery reporting.
 | Note If you observe a significant number of messages remaining in Pending status, contact Unifonic Support for further investigation. |
Improve SMS Deliverability
Deliverability refers to the percentage of messages that successfully reach their intended recipients. The following best practices can help improve delivery rates.
- Verify Recipient Phone Numbers
Ensure recipient phone numbers are valid and correctly formatted.
Check that each phone number includes:
- A valid country code.
- A valid operator prefix.
- The correct number of digits.
Invalid phone numbers may prevent message delivery.
- Register Your Sender ID
Some countries require sender ID registration before SMS messages can be delivered successfully.
For example:
- Saudi Arabia requires sender ID registration.
- Requirements may differ between countries.
If you are unsure whether sender ID registration is required, contact Unifonic Support and refer to the Getting a Sender ID documentation.
- Avoid Message Filtering
Mobile operators may block messages that violate regulatory or acceptable-use policies.
Examples include messages containing:
- Spam content
- Phishing content
- Fraudulent content
- Inappropriate language
When including URLs in SMS messages:
- Use your organization's branded domain whenever possible.
- Avoid public URL shorteners such as Bitly or TinyURL.
- Consider using Unifonic URL shortening services if available.
- Validate API Integrations Before Production Use
Before sending production traffic through the API:
- Send a small number of test messages.
- Verify that API requests are accepted successfully.
- Confirm that the API returns successful responses.
- Verify that messages are delivered to the intended recipient devices.
Testing before production deployment can help identify configuration issues before sending high-volume traffic.