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If you want to skip this guide, take note of the following important information:

• By default only SMS send to Belgium, Luxemburg, Netherlands and France is allowed
  Go to Country Permissions to unlock other countries
• We restrict sending SMS to the same phone number to 5 times per hour
  See Spam prevention below

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**Want to test without paying for SMS ? **

To test SMS API or other products without sending SMS that could incur fees is to remove all countries from the Country Permissions then all SMS will be rejected and you will still be able to see the stats, activities and receive webhooks for those messages.

Please note than load testing is strictly prohibited and any abuse of this will incure an automatic closure of your account.

How it works

SMS (Short Message Service) is one of the most widely recognized communication channels among mobile users, having been one of the earliest to emerge. It remains a dependable method for reaching customers, ensuring high-quality message delivery.

Unlike messaging apps that require internet access, SMS works seamlessly across all mobile devices without connectivity constraints. Its speed and security make it especially well-suited for critical communications like two-factor authentication.

Overall, SMS remains a straightforward and effective way to engage with your audience.

SMS relies on mobile signal coverage to deliver messages. However, if a recipient is temporarily out of range, messages are automatically stored for up to 72 hours and will be delivered once the device reconnects to the network.

A standard SMS can contain up to 160 or 70 characters when using Unicode encoding. If a message exceeds these limits, it is split into multiple parts that are reassembled upon delivery (For more information on the length of an SMS and the accepted characters: https://docs.naxai.com/edit/status-error-codes). SMS supports only text content and does not accommodate media files.

Sender Identities

In Naxai SMS, a Sender refers to the name or number that appears on a recipient’s device when they receive a message. This identifier—whether it’s a company name, department, or government entity—helps build trust and encourages engagement.

Regulations and Registration

Different countries and mobile networks have varying rules for SMS usage. In many cases, sender IDs must be registered before messages can be sent. The registration process differs by operator and may involve pre-approvals, message templates, or supporting documentation. Processing times depend on the complexity of the requirements. For assistance, reach out to your Naxai account manager.

Short codes and Long numbers

These numeric senders are especially effective for transactional or conversational messages, as they appear as familiar, localized numbers.

Short Codes

Short Codes are 4–6 digit number, ideal for high-volume or interactive messaging.
Example of Short Codes in Belgium: 8810, 8686

Long Numbers or 10-DLC

Long Codes are standard 10-digit numbers, often used for two-way communication like customer support.

Ownership

A dedicated number belongs exclusively to you. All messages are automatically associated with your account.

In certain countries, shared senders (or shared sender IDs) are also available. These are not tied to a single business or user but are used by multiple companies or individuals on the same SMS platform. Shared senders are often chosen for their cost-effectiveness and ease of use, particularly for smaller campaigns or businesses that do not require a unique sender ID.

Using a dedicated sender instead of a shared one enhances brand visibility and recognition.

Alphanumeric Sender ID

Combines letters and numbers (up to 11 characters).

Best for one-way communication, such as marketing or alerts.
Replies are not supported, and Alphanumeric Sender IDs are not supported in all countries.
Some countries require pre-registration.

Example of Alphanumeric sender IDs : "MyBrand" , "MYSHOP"

Sender Services

Naxai offers a feature called Sender Services, which enables you to configure how sender identities are used based on the recipient’s country.

Unlike simply selecting a "from" number when sending SMS, Sender Services provide more flexibility and relevance.

By default, Sender Services utilise shared shortcodes and A2P long numbers tailored to each destination country.

You can associate Sender Services with either marketing or non-marketing activities:

• Marketing Sender Services automatically apply the SMS Suppression List.
• Non-marketing Sender Services do not use the SMS Suppression List.

We have created two Sender Services for you, which can be used directly via shared short codes and long numbers.
You can adapt those Sender Services or create new ones.

Length of SMS and Characters supported

Review how SMS length is calculated and how special characters can affect the length of messages.

Enable SMS Country Permissions

Naxai proposes a Country Permissions add-on to let you decide which countries your applications can send SMS to. This will help you protect your account against SMS Pumping fraud or possible misuse.

Sending SMS

Naxai proposes several products for sending SMS depending on your business case and integration capabilities.

• Quick SMS: used to send individual SMS with a simple web interface.
• SMS Broadcasts: used to send large SMS one-way (Bulk) to recipients by uploading a file or using the contacts.
• Email to SMS: converts email into SMS, adding SMS capabilities to your email Inbox
• FTP to SMS: to automate campaigns and bulk sending with the file ingestion via FTP.
• SMS API: to programmatically send SMS using our Naxai API.
• SMPP: to send SMS using SMPP for large volume and specific integrations.

Spam prevention

To prevent spam or unexpected sending of SMS, Naxai will allow sending maximum 5 SMS to the same destination per hour. If your use case requires sending more than 5 SMS, please contact our support team.

Reports and Activity Logs

SMS Activity logs and SMS Reporting are products that help you measure and understand the status of SMS messages sent.

SMS Activity Logs focus on the detailed status of each message, providing an in-depth understanding of the SMS's status, time to deliver, and more.

By using SMPP or SMS API, delivery notifications (SMS status report) are provided via SMPP or Webhooks for SMS API, allowing you to automate your reporting based on the SMS Statuses.

Data retention

Phone numbers and SMS content are stored in the SMS Activity Logs, and a data retention policy is applied to this information.

By default, this data is retained for 30 days.

It is possible to extend or modify this retention period by contacting our support team.

Content redaction

You can enhance data security by enabling content redaction for phone numbers and/or SMS messages.

When this feature is enabled:

• Phone numbers are partially masked (last digits are hidden)
• SMS content is replaced with the following placeholder: #_**CONTENT_REPLACED_BY_SETTINGS**_#

To enable this feature, please contact our support team.