Malta SMS Guide: API Integration, GDPR Compliance & Best Practices

Send SMS to Malta with confidence using this developer-focused implementation guide. Malta's telecommunications market includes three major operators (Epic, GO, Melita) supporting alphanumeric sender IDs, concatenated messages, and E.164 number formatting (+356). This guide covers Malta SMS API integration with Twilio, Sinch, MessageBird, and Plivo, GDPR consent requirements, Malta Communications Authority (MCA) regulations, sender ID best practices, and technical implementation patterns for reliable SMS delivery to Maltese mobile numbers.

Malta SMS Market Overview

Market Conditions: Malta has a highly developed mobile telecommunications market with three mobile network operators (MNOs) providing comprehensive coverage across the islands. As of 2024-2025, Epic (formerly Vodafone Malta, rebranded in 2021) leads the market with approximately 42% share, followed by GO with 35–50%, and Melita with approximately 23%.

Mobile Penetration: Malta reached a mobile penetration rate of 133.4% by end of 2024 (up from 133.0% in 2023), with 766,620 mobile subscriptions serving a population of approximately 575,000. This high penetration rate reflects multiple subscriptions per capita, with post-paid plans surpassing pre-paid subscriptions for the first time in Q1 2024, reaching 53.4% of the market by year-end.

While OTT messaging apps like WhatsApp and Facebook Messenger are popular, SMS remains a crucial channel for business communications and authentication services. The market shows a balanced mix of Android and iOS devices, with both platforms well-represented among Maltese mobile users. Epic is actively expanding its 5G network with EIB funding, targeting nationwide coverage by end-2024.

Sources: Malta Communications Authority Q4 2024 Data Report (April 2025); Malta Telecoms Market Report 2024; EQT Infrastructure; European Investment Bank

SMS Features and Technical Capabilities for Sending to Malta

When you send SMS to Malta, the network supports concatenated messages (long SMS) and alphanumeric sender IDs without pre-registration. However, two-way SMS functionality is not supported by major providers.

Two-Way SMS Support

Major SMS providers don't support two-way SMS in Malta. Design your SMS strategies around one-way communication flows. This limitation is primarily due to carrier restrictions and the widespread use of alphanumeric sender IDs, which inherently don't support replies.

Alternative approaches:

• Include web links with tracking parameters for response collection
• Use URL shorteners with analytics to track engagement
• Implement webhook-based confirmation systems
• Direct users to dedicated landing pages for feedback

Concatenated Messages (Long SMS)

Support: Yes, concatenation is supported for most sender ID types.

Message length rules:

• GSM-7 encoding: Single message supports 160 characters. Concatenated messages split into 153-character segments (7 characters reserved for reassembly headers).
• Unicode (UCS-2) encoding: Single message supports 70 characters. Concatenated messages split into 67-character segments (3 characters reserved for headers).

Encoding considerations: Messages automatically switch to UCS-2 encoding when they contain any Unicode character (emojis, extended Latin characters, special quotation marks like " " instead of " "). This reduces the character limit and increases segment costs.

Special characters triggering Unicode encoding:

• Emojis (😀, 👍, ❤️, etc.)
• Curly quotes and apostrophes (" " ' ' instead of " ' )
• Em dashes and en dashes (— – instead of -)
• Extended Latin characters not in GSM-7 (ë, ñ, ü in some contexts)
• Non-Latin scripts (Arabic, Chinese, Cyrillic, etc.)

Cost implications: Billing is per segment sent. A 161-character GSM-7 message sends as 2 segments (153 + 8 characters), while a 71-character message containing one emoji also sends as 2 segments due to UCS-2 encoding.

Source: Twilio SMS Character Limits; Infobip Concatenated Messages

MMS Support

MMS messages automatically convert to SMS with an embedded URL link to the media content. This ensures compatibility while allowing you to share rich media with your audiences.

File size and format guidelines:

• Recommended maximum size: 600 KB for optimal carrier compatibility
• Tier 1 carriers (Epic, GO, Melita): Support up to 1 MB
• Supported formats: JPEG, PNG, GIF (images); MP4, M4V, 3GP (video); MP3, AMR (audio); vCard, vCalendar, PDF (documents)

URL hosting requirements:

• Use HTTPS-secured hosting with valid SSL certificates
• Ensure URLs are accessible without authentication
• Host on registered, reputable domains to avoid carrier filtering
• Implement CDN delivery for faster loading times

Fallback behavior: When MMS delivery fails or the recipient's device doesn't support MMS, carriers automatically deliver an SMS with a link to view the media content via a web browser. Link expiration times vary by provider (typically 30–90 days).

Source: Twilio MMS File Types and Limits

Phone Number Format and Portability

Number Portability in Malta

Malta offers number portability under an enhanced framework that came into force on June 1, 2023, following MCA Decision Notice (November 2022) reflecting provisions from the European Electronic Communications Code (EECC). Users can keep their phone numbers when switching carriers, with porting completed within one working day. Upon porting, subscribers are bound to the new service provider for a minimum of two months from the effective porting date. This doesn't significantly impact SMS delivery or routing – messages automatically route to the correct carrier.

Source: Malta Communications Authority, Enhanced Number Portability Framework (effective June 1, 2023)

Sending SMS to Landlines

Malta mobile numbers are 8 digits long and follow the E.164 format: +356 XXXX XXXX. Landline numbers also use 8 digits but typically start with 21 for the main island and 22 for Gozo (e.g., +356 21234567 for landlines vs. +356 7912 3456 or +356 9912 3456 for mobiles). Mobile numbers typically start with 79 or 99.

Number validation: Identify landlines before sending by checking if the number starts with 21, 22, or 23 (landline prefixes). Mobile numbers start with 77, 79, 99, or other mobile-designated prefixes.

You cannot send SMS to landline numbers in Malta. Attempts result in failed delivery with a 400 response error (code 21614), and you incur no charges.

Source: Telephone numbers in Malta (Wikipedia); Malta Phone Number Format (JustCall)

Malta SMS Compliance: GDPR Requirements and MCA Regulations

As an EU member state, Malta requires SMS marketing compliance with GDPR (General Data Protection Regulation) and local telecommunications regulations overseen by the Malta Communications Authority (MCA). Before you send SMS to Malta, ensure your communications comply with both EU-wide data protection laws and Malta-specific guidelines. Malta's primary data protection legislation is the Data Protection Act (Chapter 586), which implements GDPR, and the Processing of Personal Data (Electronic Communications Sector) Regulations (Subsidiary Legislative 586.01), which implements the ePrivacy Directive. The Information and Data Protection Commissioner (IDPC) conducts enforcement.

GDPR Penalties: Under GDPR Article 83, violations can result in administrative fines up to €20 million or 4% of total worldwide annual turnover (whichever is higher) for severe infringements including lack of consent, unlawful processing, or failure to honor data subject rights. Less severe violations may result in fines up to €10 million or 2% of annual turnover. In Malta, IDPC has imposed fines ranging from €15,000 to €65,000, with the highest fine to date being €65,000 for security principle violations.

Commercial Provider Authorization: To provide commercial electronic communications services, notify the Malta Communications Authority for a General Authorisation under the Electronic Communications (Regulation) Act (Chapter 399 of the Laws of Malta).

MCA Notification Process:

1. Complete Form A of the General Authorisation Notification Form
2. Submit Memorandum & Articles of Association (if new provider)
3. For non-EU providers: Register as an overseas company with Malta Business Registry
4. Provide official Malta address for service of notices
5. Submit by registered mail or in person to MCA, Valletta Waterfront, Pinto Wharf, Floriana FRN 1913
6. Timeline: MCA updates the Register of Authorised Undertakings within 5 working days of receipt of a correctly completed notification
7. You may start operations immediately upon proper notification

Sources: Malta Information and Data Protection Commissioner; MCA General Authorisation Notification Form; IDPC Decisions; GDPR Fines Article 83

How to Obtain GDPR-Compliant SMS Consent in Malta

Explicit consent requirements:

• Ensure consent is freely given, specific, informed, and unambiguous
• Obtain written or electronic consent before sending marketing messages through affirmative action (pre-ticked boxes aren't acceptable)
• Present consent in clear, plain language, distinguishable from other written agreements
• Maintain consent records and make them easily accessible
• State the purpose of communication during opt-in
• Use double opt-in for marketing campaigns (recommended)
• Allow data subjects to withdraw consent at any time

Documentation best practices:

• Store timestamp and source of consent
• Maintain detailed records of opt-in methods
• Audit your consent database regularly
• Enable easy access to consent records for compliance verification

HELP/STOP and Other Commands

• Support STOP, CANCEL, UNSUBSCRIBE, and OPT-OUT commands
• Provide contact information and opt-out instructions via HELP command
• Recognize commands in both English and Maltese
• Respond to opt-out requests immediately with confirmation

Maltese language commands:

• STOP / IEQAF (stop)
• CANCEL / IKKANĊELLA (cancel)
• HELP / GĦAJNUNA (help)
• UNSUBSCRIBE / NEĦĦI ISEM (unsubscribe)

Example HELP/STOP response messages:

• English: "You've been unsubscribed from [Company] SMS. Reply HELP for support or visit [URL]."
• Maltese: "Ġejt megħliq minn SMS ta' [Company]. Irrispondi GĦAJNUNA għal appoġġ jew żur [URL]."

Do Not Call / Do Not Disturb Registries

Malta doesn't maintain a centralized Do Not Call registry. You must:

• Maintain your own suppression lists
• Honor opt-out requests within 24 hours
• Clean contact databases regularly
• Implement proper opt-out tracking systems

Time Zone Sensitivity

Malta observes Central European Time (CET/CEST).

• Recommended sending hours: 8:00 AM to 8:00 PM local time
• Avoid sending: Sundays and public holidays
• Emergency messages: Send outside standard hours only when urgent

Malta Public Holidays 2025 (avoid sending on these dates):

• January 1 – New Year's Day
• February 10 – Feast of St. Paul's Shipwreck
• March 19 – Feast of St. Joseph
• March 31 – Freedom Day
• April 18 – Good Friday
• April 20 – Easter Sunday
• May 1 – Workers' Day
• June 7 – Sette Giugno
• June 29 – Feast of St. Peter and St. Paul
• August 15 – Feast of the Assumption
• September 8 – Feast of Our Lady of Victories
• September 21 – Independence Day
• December 8 – Feast of the Immaculate Conception
• December 13 – Republic Day
• December 25 – Christmas Day

Source: Malta Public Holidays (Office Holidays); Malta Government Public Holidays

Sender ID Options for Sending SMS to Malta

Alphanumeric Sender ID

Operator network capability: Fully supported Registration requirements: No pre-registration required; fully dynamic usage allowed Sender ID preservation: Sender IDs are preserved and displayed as sent

Character limits and restrictions:

• Maximum length: 11 characters
• Minimum length: 3 characters (some carriers may require this)
• Allowed characters: Letters (A-Z, a-z), numbers (0-9), and space character (ASCII 32)
• Case sensitivity: Case is preserved as sent
• Prohibited characters: Special symbols (@, #, $, %, etc.), punctuation marks (except space)

Best practices:

• Use recognizable brand names or service identifiers (e.g., "YourBank", "FlashSale")
• Avoid all-numeric sender IDs (use alphanumeric type to differentiate from phone numbers)
• Keep it short and memorable (7–9 characters is optimal)
• Maintain consistency across campaigns for brand recognition

Restricted sender IDs: Don't impersonate government agencies, emergency services, or well-known brands. Carriers may block sender IDs that appear fraudulent or misleading.

Source: Infobip Alphanumeric Sender ID; Twilio Alphanumeric Sender ID

Long Codes

Domestic vs. international:

• Domestic long codes: Not supported
• International long codes: Fully supported

Sender ID preservation: Yes, original sender ID is preserved Provisioning time: Immediate to 24 hours Use cases: Ideal for transactional messages and two-factor authentication

Short Codes

Support: Not currently supported in Malta Provisioning time: N/A Use cases: N/A

Restricted SMS Content, Industries, and Use Cases

Malta follows EU guidelines for restricted content while maintaining specific local restrictions:

Restricted industries:

• Unregulated gambling services
• Unauthorized financial services
• Adult content
• Prescription medications

Regulated industries (requiring special permits):

• Financial services (Malta Financial Services Authority [MFSA] approval required)
• Healthcare services (Ministry of Health oversight)
• Gaming companies (Malta Gaming Authority [MGA] license required)

Content Filtering

Carrier filtering rules:

• Carriers may block links from unknown domains
• Carriers may filter messages containing certain keywords
• High-frequency sending patterns can trigger blocks

Common spam trigger words (avoid or use sparingly):

• "FREE", "Winner", "Congratulations" (all caps)
• "Click here now", "Urgent action required"
• "Limited time", "Act now", "Claim your prize"
• Excessive use of exclamation marks (!!!)
• Multiple URLs in a single message
• Phrases mimicking financial institutions without authorization

Best practices to avoid filtering:

• Use registered domains for links
• Avoid spam trigger words
• Maintain consistent sending patterns
• Include clear sender identification
• Use URL shorteners from reputable services (bit.ly, tinyurl.com)
• Warm up new sending domains gradually

Best Practices for Sending SMS to Malta

SMS Messaging Strategy for Malta

• Keep messages under 160 characters when possible
• Include clear call-to-action
• Personalize using recipient's name or relevant details
• Maintain professional tone and branding

Sending Frequency and Timing

• Limit to 2–4 messages per month per recipient
• Respect local holidays and cultural events
• Avoid sending during weekends
• Space out bulk campaigns to prevent network congestion

Localization

• Support both English and Maltese languages
• Consider cultural context and local customs
• Use appropriate date and time formats
• Include country code in phone numbers

Maltese language considerations:

• Malta is officially bilingual (Maltese and English)
• Business communications are commonly in English
• Government and formal communications often use both languages
• For wider reach, consider bilingual messages or English (universally understood)

Date and time formats for Malta:

• Date format: DD/MM/YYYY (e.g., 15/03/2025)
• Time format: 24-hour clock (e.g., 14:30) or 12-hour with AM/PM
• Time zone reference: CET/CEST (UTC+1/UTC+2)

Opt-Out Management

• Process opt-outs within 24 hours
• Maintain centralized opt-out database
• Confirm opt-out with acknowledgment message
• Audit your opt-out list regularly

Testing and Monitoring

• Test across all major Maltese carriers
• Monitor delivery rates by carrier
• Track engagement metrics
• Test opt-out functionality regularly

Key metrics to track:

• Delivery rate: Target >95% (acceptable threshold: >90%)
• Bounce rate: Target <5% (investigate if >10%)
• Opt-out rate: Target <2% per campaign (review content if >5%)
• Response rate (for campaigns with CTAs): Industry average 8–15%
• Conversion rate: Varies by use case (2–5% typical for promotional campaigns)

Monitoring best practices:

• Set up automated alerts for delivery rates below 90%
• Monitor carrier-specific delivery patterns
• Track time-of-day performance
• Review error codes and patterns weekly

SMS API Integration: Send SMS to Malta with Code Examples

Twilio

Twilio SMS API provides robust Malta SMS support with alphanumeric sender IDs and delivery reporting. Authenticate using your Account SID and Auth Token to send SMS to Malta programmatically.

import * as Twilio from 'twilio';

// Initialize Twilio client with environment variables
const client = new Twilio(
  process.env.TWILIO_ACCOUNT_SID,
  process.env.TWILIO_AUTH_TOKEN
);

// Function to send SMS to Malta
async function sendSMSToMalta(
  to: string,
  message: string,
  senderId: string
) {
  try {
    // Ensure number is in E.164 format for Malta (+356)
    const formattedNumber = to.startsWith('+356') ? to : `+356${to}`;

    const response = await client.messages.create({
      body: message,
      from: senderId, // Alphanumeric sender ID or phone number
      to: formattedNumber,
      statusCallback: 'https://your-webhook-url.com/delivery-status', // For delivery reports
    });

    console.log(`Message sent successfully! SID: ${response.sid}`);
    return response;
  } catch (error) {
    console.error('Error sending message:', error);
    throw error;
  }
}

Sinch

Sinch SMS API offers straightforward Malta SMS integration with alphanumeric sender ID support and comprehensive delivery reporting.

import { SinchClient } from '@sinch/sdk-core';

// Initialize Sinch client
const sinchClient = new SinchClient({
  projectId: process.env.SINCH_PROJECT_ID,
  keyId: process.env.SINCH_KEY_ID,
  keySecret: process.env.SINCH_KEY_SECRET,
});

// Function to send SMS using Sinch
async function sendSinchSMS(
  to: string,
  message: string,
  senderId: string
) {
  try {
    const response = await sinchClient.sms.batches.send({
      sendSMSRequestBody: {
        to: [to],
        from: senderId,
        body: message,
        delivery_report: 'summary' // Enable delivery reporting
      }
    });

    console.log('Message sent:', response.id);
    return response;
  } catch (error) {
    console.error('Sinch SMS Error:', error);
    throw error;
  }
}

MessageBird

MessageBird SMS API provides reliable SMS delivery to Malta with real-time delivery reporting and webhook support.

import { MessageBird } from 'messagebird';

// Initialize MessageBird client
const messagebird = new MessageBird(process.env.MESSAGEBIRD_API_KEY);

// Function to send SMS via MessageBird
async function sendMessageBirdSMS(
  to: string,
  message: string,
  senderId: string
): Promise<any> {
  return new Promise((resolve, reject) => {
    messagebird.messages.create({
      originator: senderId,
      recipients: [to],
      body: message,
      reportUrl: 'https://your-webhook-url.com/delivery-reports'
    }, (err, response) => {
      if (err) {
        console.error('MessageBird Error:', err);
        reject(err);
      } else {
        console.log('Message sent:', response.id);
        resolve(response);
      }
    });
  });
}

Plivo

Plivo SMS API offers reliable Malta SMS delivery with high-volume throughput and competitive pricing.

import * as plivo from 'plivo';

// Initialize Plivo client
const client = new plivo.Client(
  process.env.PLIVO_AUTH_ID,
  process.env.PLIVO_AUTH_TOKEN
);

// Function to send SMS via Plivo
async function sendPlivoSMS(
  to: string,
  message: string,
  senderId: string
) {
  try {
    const response = await client.messages.create({
      src: senderId,
      dst: to,
      text: message,
      url: 'https://your-webhook-url.com/delivery-status'
    });

    console.log('Message sent:', response.messageUuid);
    return response;
  } catch (error) {
    console.error('Plivo Error:', error);
    throw error;
  }
}

API Rate Limits and Throughput

Provider-specific rate limits:

• Twilio: Default 1 message/second per destination; inbound queued at 500 messages/second; contact support for higher limits
• Sinch: 800 requests/second across all apps and endpoints at project level
• MessageBird: Variable by account tier; typically 10–50 messages/second; contact support for enterprise limits
• Plivo: Default 10 messages/second; higher limits available on request

How to request rate limit increases:

1. Contact your provider's support or account manager
2. Provide use case details and expected volume
3. Demonstrate compliance with anti-spam policies
4. Some providers require account history or minimum spend
5. Enterprise agreements often include custom rate limits

Best practices:

• Implement exponential backoff for retry logic
• Use batch APIs for high-volume sending
• Consider queue implementation for large campaigns:

import Queue from 'bull';

// Initialize message queue
const smsQueue = new Queue('sms-queue', {
  redis: process.env.REDIS_URL
});

// Add rate limiting
smsQueue.process(10, async (job) => {
  const { to, message, senderId } = job.data;
  await sendSMS(to, message, senderId);
});

Sources: Twilio Rate Limits; Sinch API Rate Limits

Error Handling and Reporting

Common SMS error codes:

• 21614: 'To' number is not a valid mobile number (landline, invalid, or incorrectly formatted)
• 21408: Message blocked or geo-permissions not enabled for destination region
• 30003: Unreachable destination (device off, out of coverage, or number invalid)
• 30004: Message blocked by carrier (spam filters triggered)
• 30005: Unknown destination handset (number no longer in service)
• 30006: Landline or unreachable carrier
• 30007: Message filtered (content flagged by carrier)
• 30008: Unknown error (carrier-side issue)

Retry strategies:

• 21614, 21408, 30006: Don't retry (permanent failures; fix number format or permissions)
• 30003, 30005: Retry after 1–4 hours (may be temporary network issues); max 2–3 retries
• 30004, 30007: Review and modify content before retry; implement cooling period
• 30008: Retry with exponential backoff (1 min, 5 min, 15 min); max 3 retries

Circuit breaker pattern:

class CircuitBreaker {
  private failureCount = 0;
  private lastFailureTime: number | null = null;
  private readonly threshold = 5;
  private readonly timeout = 60000; // 1 minute

  async execute<T>(fn: () => Promise<T>): Promise<T> {
    if (this.isOpen()) {
      throw new Error('Circuit breaker is OPEN');
    }

    try {
      const result = await fn();
      this.onSuccess();
      return result;
    } catch (error) {
      this.onFailure();
      throw error;
    }
  }

  private isOpen(): boolean {
    if (this.failureCount >= this.threshold) {
      if (this.lastFailureTime && Date.now() - this.lastFailureTime > this.timeout) {
        this.reset();
        return false;
      }
      return true;
    }
    return false;
  }

  private onSuccess() {
    this.reset();
  }

  private onFailure() {
    this.failureCount++;
    this.lastFailureTime = Date.now();
  }

  private reset() {
    this.failureCount = 0;
    this.lastFailureTime = null;
  }
}

// Example error handling middleware
interface SMSError extends Error {
  code: string;
  status: number;
}

function handleSMSError(error: SMSError) {
  switch (error.code) {
    case '21614':
      console.error('Invalid number format - check E.164 format or landline');
      // Don't retry - permanent error
      break;
    case '21408':
      console.error('Geo-permissions not enabled for this region');
      // Check account settings, enable region, then retry
      break;
    case '30003':
      console.error('Unreachable destination - may be temporary');
      // Retry after delay
      break;
    case '30004':
      console.error('Message blocked by carrier - review content');
      // Review message content before retry
      break;
    default:
      console.error('Unknown error:', error);
      // Implement exponential backoff retry
  }

  // Log to monitoring service
  logger.error({
    error: error,
    timestamp: new Date(),
    service: 'sms-service'
  });
}

Sources: Twilio Error 21614; Twilio Error 21408

Frequently Asked Questions About Sending SMS to Malta

What is the country code for sending SMS to Malta?

Malta's international country code is +356. Format numbers in E.164 standard: +356 followed by the 8-digit local number (e.g., +35621234567).

Do I need to register sender IDs for Malta SMS?

No. Malta supports alphanumeric sender IDs without pre-registration. Dynamic usage is fully allowed, and sender IDs are preserved and displayed as sent to recipients.

Is two-way SMS supported in Malta?

No, major SMS providers don't support two-way SMS in Malta. Design your SMS strategies around one-way communication flows for delivery confirmations, alerts, and marketing messages.

What GDPR requirements apply to SMS marketing in Malta?

You must obtain explicit consent that is freely given, specific, informed, and unambiguous before sending marketing messages. Consent must be obtained through affirmative action (pre-ticked boxes aren't acceptable). Maintain detailed consent records with timestamps, and allow data subjects to withdraw consent at any time.

Which SMS API providers work best for Malta?

Twilio, Sinch, MessageBird, and Plivo all provide reliable SMS delivery to Malta with support for alphanumeric sender IDs. All providers support E.164 number formatting and offer comprehensive delivery reporting.

What are the recommended sending hours for SMS in Malta?

Send SMS between 8:00 AM to 8:00 PM local time (Central European Time, CET/CEST). Avoid sending on Sundays and public holidays unless messages are urgent or emergency-related.

How long does number portability take in Malta?

Under Malta's enhanced number portability framework (effective June 1, 2023), porting completes within one working day. Subscribers are bound to the new provider for a minimum of two months after porting.

What is the maximum SMS length for Malta?

Standard SMS supports 160 characters for GSM-7 encoding or 70 characters for Unicode (UCS-2) encoding. Longer messages are automatically split into concatenated segments and rejoined at the recipient's device.

Can I send SMS to landline numbers in Malta?

No. SMS to landline numbers isn't possible in Malta. Attempts fail with a 400 response error (code 21614), and you incur no charges.

Do I need MCA authorization to send commercial SMS in Malta?

If you provide commercial electronic communications services, you must notify the Malta Communications Authority for a General Authorisation under the Electronic Communications (Regulation) Act (Chapter 399).

Recap and Additional Resources

Key Takeaways

1. Compliance priorities

   • Obtain explicit consent before sending marketing messages
   • Honor opt-out requests within 24 hours
   • Maintain proper documentation with timestamps and sources

2. Technical best practices

   • Format numbers in E.164 standard (+356)
   • Implement proper error handling and retry logic
   • Monitor delivery rates across carriers

3. Next steps

   • Review Malta Communications Authority guidelines
   • Set up monitoring and logging infrastructure
   • Test with small volumes before scaling to full campaigns

Additional Resources

• Malta Communications Authority
• GDPR Guidelines for SMS Marketing
• Malta Business Registry

Technical documentation:

• Twilio Malta Guidelines
• Sinch API Documentation
• MessageBird API Reference
• Plivo SMS API Guide