San Marino SMS Best Practices, Compliance, and Features

Sending SMS messages to San Marino (+378) requires understanding specific compliance requirements, phone number formats, and technical limitations. This comprehensive guide covers everything you need to know about SMS delivery to San Marino, including GDPR-aligned Law 171 compliance, alphanumeric sender IDs, message character limits, and API integration examples for Twilio, Sinch, Plivo, and MessageBird.

San Marino SMS Market Overview

Market Conditions: San Marino maintains modern telecommunications infrastructure despite its small population of approximately 33,600 (DataReportal, 2024). Mobile teledensity reached 121.8% in December 2022 (approximately 40,000 subscriptions), indicating most people use multiple devices. TIM (Telecom Italia Mobile) is the dominant carrier, providing 5G coverage to 99% of the territory as of December 2018.

Delivery Performance: Expect delivery rates above 95% to mobile numbers when you use properly formatted sender IDs and compliant content. Messages typically deliver in 3–10 seconds during normal network conditions.

Key SMS Features and Capabilities in San Marino

San Marino supports basic SMS functionality with limitations on advanced features. All services route through Italian carriers because San Marino lacks domestic telecommunication infrastructure.

Two-Way SMS Support

San Marino does not support two-way SMS according to current provider specifications. You cannot receive replies through standard A2P channels.

Workarounds for two-way communication:

• Include a web link in your SMS directing recipients to a response form
• Provide a dedicated phone number for voice callback
• Direct users to email or mobile app for responses
• Use WhatsApp Business API as an alternative for interactive messaging

Concatenated Messages (Segmented SMS)

Support: San Marino does not support concatenated messages.

Message length rules: Standard SMS character limits apply – 160 characters for GSM-7 encoding and 70 characters for Unicode (UCS-2).

Encoding considerations: Both GSM-7 and UCS-2 encodings are supported, though messages cannot be concatenated.

Character counting and truncation:

• GSM-7 encoding: Messages exceeding 160 characters will be truncated at the 160-character mark
• UCS-2 encoding (Unicode): Messages exceeding 70 characters will be truncated at 70 characters
• Extended GSM characters (e.g., |, ^, €, {, }, [, ], ~, \\) count as 2 characters each
• Calculate message length accounting for encoding before sending to detect potential truncation
• Test with your SMS provider's character counter or implement length validation in your application

Example truncation detection:

function checkMessageTruncation(message) {
  const extendedChars = /[\|\^\€\{\}\[\]\~\\]/g;
  let length = message.length;
  const extendedCount = (message.match(extendedChars) || []).length;
  length += extendedCount; // Extended chars count as 2

  const isUnicode = /[^\x00-\x7F]/.test(message);
  const limit = isUnicode ? 70 : 160;

  return {
    length,
    limit,
    willTruncate: length > limit,
    charactersOver: Math.max(0, length - limit)
  };
}

MMS Support

MMS messages are automatically converted to SMS with an embedded URL link. Host multimedia content separately and link it within the message body.

Best practices for multimedia content hosting:

• Use HTTPS URLs for security and deliverability
• Keep URLs short (use URL shorteners like bit.ly, tinyurl.com)
• Host images at recommended sizes: max 1 MB, 640×480 px for compatibility
• Set appropriate cache headers for faster loading
• Ensure landing pages are mobile-optimized
• Monitor link click-through rates to measure engagement

San Marino Phone Number Format (+378)

Number Portability

San Marino does not offer number portability. Mobile numbers remain tied to their original carriers.

Carrier identification: According to Wikipedia, San Marino phone numbers follow these patterns:

• Mobile numbers start with 6 (format: +378 6XXX XXXX)
• Landlines start with 0, 8, or 9
• IP telephony services use 5
• Premium numbers use 7

Sending SMS to Landlines

You cannot send SMS to landline numbers in San Marino. Attempts to send to landlines fail with a 400 response error (error code 21614) from messaging APIs. These messages won't appear in logs, and you won't be charged.

Landline detection validation:

function isSanMarinoMobile(phoneNumber) {
  // Remove country code and formatting
  const cleaned = phoneNumber.replace(/[\s\-\(\)]/g, '');

  // Check if it starts with +378 6 (mobile) or 378 6
  if (cleaned.match(/^\+?3786/)) {
    return true;
  }

  // Landlines start with 0, 8, or 9
  if (cleaned.match(/^\+?378[089]/)) {
    return false; // Landline
  }

  return null; // Unknown/invalid
}

San Marino SMS Compliance and GDPR Regulations

San Marino follows Data Protection Law (Law No. 171 of 21 December 2018), which aligns closely with GDPR principles. The Authority for Personal Data Protection (Autorità Garante per la Protezione dei Dati Personali) oversees compliance. All SMS communications must adhere to these standards, particularly regarding personal data processing and storage.

Penalties for non-compliance: Following GDPR-aligned principles, penalties can reach up to €20 million or 4% of global annual turnover (whichever is higher) for serious violations including:

• Infringements of basic processing principles (Articles 5, 6, 9)
• Violations of data subjects' rights (Articles 12-22)
• Failure to obtain proper consent (Article 7)
• Unauthorized international data transfers

Data retention requirements:

• Retain consent records for the duration of the relationship plus 3 years
• Delete personal data when no longer necessary for original purpose
• Document data retention periods in your privacy policy
• Implement automated deletion processes for expired data
• Maintain audit logs of data processing activities for at least 1 year

Consent and Opt-In Requirements

Explicit Consent Requirements:

• Obtain written or electronic consent before sending marketing messages
• Ensure consent is freely given, specific, and informed
• Keep detailed records of when and how you obtained consent
• Provide clear information about how you'll use the phone number
• Include your business name and purpose in consent requests

Consent refresh: Re-confirm consent every 24 months for marketing communications, or when you significantly change how you process data. Transactional messages do not require consent renewal if within the original scope.

HELP/STOP and Other Commands

• Include clear opt-out instructions in all marketing messages
• Honor STOP commands immediately (within 1 hour)
• Provide HELP responses in Italian (primary language) and English
• Support common keywords: STOP, ANNULLA, AIUTO, INFO, HELP
• Maintain logs of all opt-out requests and their processing dates

Example message templates:

Italian HELP response:

English HELP response:

Italian STOP confirmation:

English STOP confirmation:

Implementation for keyword detection:

function processInboundSMS(messageBody, phoneNumber) {
  const normalized = messageBody.trim().toUpperCase();

  const stopKeywords = ['STOP', 'ANNULLA', 'CANCEL', 'UNSUBSCRIBE'];
  const helpKeywords = ['HELP', 'AIUTO', 'INFO', 'INFORMATION'];

  if (stopKeywords.includes(normalized)) {
    return handleOptOut(phoneNumber);
  } else if (helpKeywords.includes(normalized)) {
    return sendHelpMessage(phoneNumber);
  }

  return null; // No keyword match
}

Do Not Call / Do Not Disturb Registries

San Marino doesn't maintain a centralized Do Not Call registry. However, you should:

• Maintain your own suppression lists
• Honor opt-out requests within 24 hours
• Regularly clean contact lists to remove unsubscribed numbers
• Document all opt-out processing procedures

Time Zone Sensitivity

San Marino follows Central European Time (CET/CEST):

• Restrict messaging to 8:00 AM – 8:00 PM local time
• Avoid sending during public holidays
• Consider Italian holidays as well due to close ties
• Send emergency messages outside these hours only if necessary

San Marino Public Holidays (2025) (source):

• January 1 – New Year's Day
• January 6 – Epiphany
• February 5 – Liberation Day (Feast of St. Agatha)
• March 25 – Anniversary of the Arengo
• April 1 – Investiture of the Captains Regent
• April 20 – Easter Sunday
• April 21 – Easter Monday
• May 1 – Labour Day
• June 19 – Corpus Domini
• July 28 – Fall of Fascism and Freedom Day
• August 15 – Assumption Day
• September 3 – Foundation Day (National Day)
• October 1 – Investiture of the Captains Regent
• November 1 – All Saints' Day
• November 2 – Commemoration of the Dead
• December 8 – Immaculate Conception
• December 25 – Christmas Day
• December 26 – St. Stephen's Day

Alphanumeric Sender ID and Phone Number Options

Alphanumeric Sender ID

Operator network capability: Supported with dynamic usage allowed

Registration requirements: No pre-registration required

Sender ID preservation: Sender IDs are generally preserved as sent

Character limits and requirements (industry standard):

• Length: 3–11 characters maximum
• Allowed characters: A-Z, a-z, 0-9, and space
• Requirements: Must contain at least one letter
• Restrictions: Cannot be all numeric; no special characters except space

Best practices for effective sender IDs:

• Use your company or brand name (e.g., "AcmeCorp", "BankAlert")
• Keep it short and recognizable (6–8 characters ideal)
• Be consistent across all campaigns
• Avoid generic terms like "INFO" or "ALERT"
• Test sender ID preservation with your provider before large campaigns

Long Codes

Domestic vs. International:

• Domestic long codes are supported but not available through major providers
• International long codes are commonly used as an alternative

Sender ID preservation: Original sender IDs are typically preserved

Provisioning time: 1–3 business days for international long codes

Use cases: Ideal for transactional messages and two-factor authentication

Cost considerations: International long codes typically cost $1–5/month per number plus per-message fees ($0.01–0.05 per SMS). Domestic options, when available, may have lower per-message costs but similar monthly fees.

Short Codes

Support: San Marino does not currently support short codes

Provisioning time: Not applicable

Use cases: Not available for marketing or authentication purposes

Short codes are unavailable in San Marino due to small market size and lack of local infrastructure. Italian carrier infrastructure does not extend short code support to San Marino numbers.

Restricted SMS Content, Industries, and Use Cases

Restricted Industries and Content:

• Gambling and betting services
• Adult content or services
• Cryptocurrency promotions
• Political messaging without proper authorization
• Religious content without proper consent

Examples of violations:

• Gambling: "Win big at [Casino]! Deposit now and get 100% bonus!"
• Adult content: Any sexually explicit material or links to adult websites
• Crypto: "Invest in [Coin] now! 500% guaranteed returns!"
• Political: Unsolicited campaign messages or political fundraising
• Religious: Proselytizing or religious conversion messaging without opt-in

Enforcement and penalties: Violations result in:

• Immediate message blocking by carriers
• Sender ID blacklisting
• Account suspension by SMS providers
• GDPR fines up to €20 million or 4% of global revenue for data protection violations
• Legal action from recipients or regulatory authorities

Content Filtering

Known Carrier Filters:

• URLs from unknown domains may be blocked
• Messages containing certain keywords related to restricted industries
• Multiple exclamation marks or all-caps messages

Best Practices to Avoid Filtering:

• Use registered URL shorteners (bit.ly, t.co, etc.)
• Limit punctuation to 1–2 exclamation marks per message
• Maintain consistent sender IDs
• Include clear business identification
• Keep message content professional and straightforward

Excessive punctuation definition:

• More than 2 consecutive exclamation marks (!!!)
• More than 3 total exclamation marks in a message
• ALL CAPS for more than 3 consecutive words
• Excessive use of special characters (*****, !?!?!?)

Message formatting comparison:

Well-formatted (not filtered):

Likely to be filtered:

Best Practices for Sending SMS in San Marino

Messaging Strategy

• Keep messages under 160 characters when possible
• Include clear calls to action
• Use personalization tokens thoughtfully
• Maintain consistent branding across messages

Effective CTAs in SMS:

• Use action verbs: "Reply", "Visit", "Call", "Click"
• Create urgency: "Offer ends today", "Limited spots"
• Be specific: "Reply YES to confirm" vs. "Respond for more info"
• Single CTA per message to avoid confusion
• Make CTAs easy to act on mobile devices

Sending Frequency and Timing

• Limit marketing to 2–3 messages per week per recipient
• Respect local business hours (8 AM – 8 PM)
• Consider San Marino's public holidays
• Space out bulk sends to avoid network congestion

Optimal bulk send spacing: For campaigns over 1,000 messages:

• Distribute sends over 15–30 minute windows
• Limit to 10–50 messages per second depending on provider limits
• Use batch API endpoints when available
• Monitor delivery rates and adjust pacing if rates drop below 90%

Localization

• Use Italian as the primary language
• Consider including English for international recipients
• Use proper character encoding for special characters
• Respect local cultural norms and customs

Common Italian SMS phrases:

• "Grazie" – Thank you
• "Conferma" – Confirm
• "Cancella" – Cancel
• "Clicca qui" – Click here
• "Offerta limitata" – Limited offer
• "Il tuo codice" – Your code

Character encoding troubleshooting:

• Use UTF-8 encoding for all text
• Test accented characters (à, è, é, ì, ò, ù) before bulk sends
• Avoid emojis if not supported by your provider
• Check for proper rendering on both iOS and Android
• Consider using GSM-7 encoding when possible to maximize character count

Opt-Out Management

• Process opt-outs within 24 hours (ideally within 1 hour)
• Maintain clear opt-out records
• Include opt-out instructions in every marketing message
• Conduct regular audits of opt-out compliance

Testing and Monitoring

• Test messages across major carriers
• Monitor delivery rates closely
• Track engagement metrics
• Regularly test opt-out functionality
• Document and analyze delivery failures

Delivery rate benchmarks:

• Excellent: >98% delivery rate
• Good: 95–98% delivery rate
• Acceptable: 90–95% delivery rate
• Concerning: <90% delivery rate (investigate immediately)

Key Performance Indicators (KPIs):

• Delivery rate: Messages delivered / messages sent (target: >95%)
• Click-through rate: Link clicks / messages delivered (benchmark: 2–5% for marketing)
• Opt-out rate: Unsubscribes / messages delivered (healthy: <0.5%)
• Bounce rate: Failed messages / total sent (target: <2%)
• Response rate: Replies / messages delivered (varies by use case)

SMS API Integration Examples for San Marino

Twilio SMS API Integration

Twilio provides a REST API for sending SMS messages to San Marino. Store your account SID and auth token securely in environment variables for authentication.

import * as Twilio from 'twilio';

// Initialize Twilio client with your credentials
const client = new Twilio(
  process.env.TWILIO_ACCOUNT_SID,    // Your Account SID
  process.env.TWILIO_AUTH_TOKEN      // Your Auth Token
);

// Function to send SMS to San Marino with error handling and retry logic
async function sendSMSToSanMarino(
  to: string,
  message: string,
  senderId: string,
  maxRetries: number = 3
) {
  // Validate message length
  if (message.length > 160) {
    throw new Error('Message exceeds 160 characters and will be truncated in San Marino');
  }

  // Validate phone number format
  if (!to.match(/^\+3786\d{7,8}$/)) {
    throw new Error('Invalid San Marino mobile number format. Expected: +378 6XXX XXXX');
  }

  let attempt = 0;
  while (attempt < maxRetries) {
    try {
      const formattedNumber = to.startsWith('+378') ? to : `+378${to}`;

      const response = await client.messages.create({
        body: message,
        from: senderId,
        to: formattedNumber,
        statusCallback: 'https://your-webhook.com/status'
      });

      console.log(`Message sent successfully! SID: ${response.sid}`);
      return response;

    } catch (error: any) {
      attempt++;

      // Handle specific error codes
      if (error.code === 21614) {
        throw new Error('Invalid phone number format – likely landline');
      } else if (error.code === 21408) {
        // Rate limit exceeded - exponential backoff
        const waitTime = Math.pow(2, attempt) * 1000;
        console.log(`Rate limited. Waiting ${waitTime}ms before retry ${attempt}/${maxRetries}`);
        await new Promise(resolve => setTimeout(resolve, waitTime));
      } else if (error.code === 21611) {
        throw new Error('Message content rejected by carrier – check for restricted content');
      } else if (attempt >= maxRetries) {
        console.error('Max retries reached:', error);
        throw error;
      } else {
        // Generic retry with exponential backoff
        const waitTime = Math.pow(2, attempt) * 1000;
        await new Promise(resolve => setTimeout(resolve, waitTime));
      }
    }
  }
}

Sinch SMS API Integration

Sinch offers an API for SMS delivery to San Marino with delivery reports and batch sending.

import axios from 'axios';

class SinchSMSClient {
  private readonly apiToken: string;
  private readonly serviceId: string;
  private readonly baseUrl = 'https://sms.api.sinch.com/xms/v1';

  constructor(apiToken: string, serviceId: string) {
    this.apiToken = apiToken;
    this.serviceId = serviceId;
  }

  async sendSMS(to: string, message: string, senderId: string) {
    try {
      const response = await axios.post(
        `${this.baseUrl}/${this.serviceId}/batches`,
        {
          from: senderId,
          to: [to],
          body: message
        },
        {
          headers: {
            'Authorization': `Bearer ${this.apiToken}`,
            'Content-Type': 'application/json'
          }
        }
      );

      return response.data;
    } catch (error: any) {
      if (error.response) {
        const status = error.response.status;
        const data = error.response.data;

        if (status === 400) {
          throw new Error(`Bad request: ${data.message || 'Invalid parameters'}`);
        } else if (status === 401) {
          throw new Error('Authentication failed – check API token');
        } else if (status === 429) {
          throw new Error('Rate limit exceeded – implement retry with backoff');
        }
      }
      console.error('Sinch SMS Error:', error);
      throw error;
    }
  }

  // Batch sending optimization
  async sendBatch(recipients: string[], message: string, senderId: string) {
    // Sinch allows up to 1000 recipients per batch
    const batchSize = 1000;
    const results = [];

    for (let i = 0; i < recipients.length; i += batchSize) {
      const batch = recipients.slice(i, i + batchSize);
      const result = await this.sendSMS(batch.join(','), message, senderId);
      results.push(result);

      // Rate limiting: wait 100ms between batches
      if (i + batchSize < recipients.length) {
        await new Promise(resolve => setTimeout(resolve, 100));
      }
    }

    return results;
  }
}

MessageBird SMS API Integration

MessageBird provides an API for sending SMS to San Marino with delivery tracking.

import { MessageBird } from 'messagebird';

class MessageBirdClient {
  private client: MessageBird;

  constructor(apiKey: string) {
    this.client = new MessageBird(apiKey);
  }

  sendSMS(to: string, message: string, senderId: string): Promise<any> {
    // Validate inputs before sending
    if (!this.validatePhoneNumber(to)) {
      return Promise.reject(new Error('Invalid San Marino mobile number'));
    }

    if (message.length > 160) {
      return Promise.reject(new Error('Message too long – will be truncated'));
    }

    if (!this.validateSenderId(senderId)) {
      return Promise.reject(new Error('Invalid sender ID format'));
    }

    return new Promise((resolve, reject) => {
      this.client.messages.create({
        originator: senderId,
        recipients: [to],
        body: message,
        reportUrl: 'https://your-webhook.com/delivery-reports'
      }, (err, response) => {
        if (err) {
          reject(err);
        } else {
          resolve(response);
        }
      });
    });
  }

  private validatePhoneNumber(phone: string): boolean {
    return /^\+3786\d{7,8}$/.test(phone);
  }

  private validateSenderId(senderId: string): boolean {
    // 3-11 characters, alphanumeric + space, must contain at least one letter
    return /^(?=.*[A-Za-z])[A-Za-z0-9 ]{3,11}$/.test(senderId);
  }
}

Plivo SMS API Integration

Plivo offers SMS delivery to San Marino with detailed delivery insights.

import * as plivo from 'plivo';

class PlivoSMSClient {
  private client: plivo.Client;

  constructor(authId: string, authToken: string) {
    this.client = new plivo.Client(authId, authToken);
  }

  async sendSMS(to: string, message: string, senderId: string) {
    // Parameter validation and sanitization
    const sanitizedMessage = this.sanitizeMessage(message);
    const validatedNumber = this.validateAndFormatNumber(to);

    if (!validatedNumber) {
      throw new Error('Invalid phone number format for San Marino');
    }

    try {
      const response = await this.client.messages.create({
        src: senderId,
        dst: validatedNumber,
        text: sanitizedMessage,
        url: 'https://your-webhook.com/status',
        method: 'POST'
      });

      return response;
    } catch (error) {
      console.error('Plivo SMS Error:', error);
      throw error;
    }
  }

  private sanitizeMessage(message: string): string {
    // Remove null bytes and trim
    return message.replace(/\0/g, '').trim();
  }

  private validateAndFormatNumber(phone: string): string | null {
    const cleaned = phone.replace(/[\s\-\(\)]/g, '');

    // Check if valid San Marino mobile
    if (cleaned.match(/^\+3786\d{7,8}$/)) {
      return cleaned;
    }

    // Try to add country code if missing
    if (cleaned.match(/^6\d{7,8}$/)) {
      return '+378' + cleaned;
    }

    return null;
  }
}

API Rate Limits and Throughput

Provider-specific rate limits:

• Twilio: Default 1 message/second (can request increase to 10–100/sec)
• Sinch: Up to 150 messages/second on business plans
• MessageBird: 10–50 messages/second depending on account type
• Plivo: Default 10 messages/second (scalable with account tier)

Rate limiting implementation example:

class RateLimiter {
  private queue: Array<() => Promise<any>> = [];
  private processing = false;
  private readonly messagesPerSecond: number;
  private readonly intervalMs: number;

  constructor(messagesPerSecond: number = 10) {
    this.messagesPerSecond = messagesPerSecond;
    this.intervalMs = 1000 / messagesPerSecond;
  }

  async add<T>(fn: () => Promise<T>): Promise<T> {
    return new Promise((resolve, reject) => {
      this.queue.push(async () => {
        try {
          const result = await fn();
          resolve(result);
        } catch (error) {
          reject(error);
        }
      });

      if (!this.processing) {
        this.process();
      }
    });
  }

  private async process() {
    this.processing = true;

    while (this.queue.length > 0) {
      const fn = this.queue.shift();
      if (fn) {
        await fn();
        await new Promise(resolve => setTimeout(resolve, this.intervalMs));
      }
    }

    this.processing = false;
  }
}

// Usage
const limiter = new RateLimiter(10); // 10 messages per second

async function sendWithRateLimit(to: string, message: string) {
  return limiter.add(() => sendSMSToSanMarino(to, message, 'YourBrand'));
}

Error Handling and Reporting

Common error codes across providers:

• 21614 (Twilio): Invalid number format / landline
• 21408 (Twilio): Rate limit exceeded
• 21611 (Twilio): Message content rejected
• 400 (HTTP): Bad request – invalid parameters
• 401 (HTTP): Authentication failed
• 403 (HTTP): Forbidden – insufficient permissions
• 429 (HTTP): Too many requests – rate limited
• 500 (HTTP): Server error – retry

Retry strategies by error type:

• Transient errors (429, 503, 504): Retry with exponential backoff (3–5 attempts)
• Invalid format (21614, 400): No retry – fix input and resubmit
• Authentication (401, 403): No retry – fix credentials
• Content rejected (21611): No retry – modify message content
• Server errors (500, 502): Retry with linear backoff (2–3 attempts)

Troubleshooting Common SMS Issues in San Marino

Common Issues and Solutions

Issue: Messages not delivering

• Check phone number format (+378 6XXX XXXX for mobile)
• Verify sender ID meets alphanumeric requirements (3–11 chars, contains letter)
• Confirm message length <160 characters
• Check for restricted content (gambling, adult, crypto)

Issue: High bounce rate

• Validate numbers are mobile (start with 6), not landline (0, 8, 9)
• Check for proper international formatting (+378)
• Remove invalid numbers from list

Issue: Messages being filtered

• Reduce punctuation (max 2 exclamation marks)
• Avoid ALL CAPS
• Use reputable URL shorteners
• Test sender ID consistency

Issue: Rate limiting errors

• Implement exponential backoff
• Distribute sends over longer time windows
• Upgrade account tier for higher limits
• Use batch API endpoints

Key Takeaways

Essential SMS Best Practices for San Marino:

• Always format numbers with +378 country code
• Implement proper opt-out handling with Italian keywords
• Monitor delivery rates (target >95%)
• Follow time window restrictions (8 AM – 8 PM local time)
• Maintain proper consent records per GDPR-aligned Law 171

Next Steps

Implementation Checklist:

1. Review San Marino's Data Protection Law (Law No. 171) – Est. time: 2 hours
2. Implement proper consent collection mechanisms – Est. time: 1–2 days development
3. Set up delivery monitoring systems – Est. time: 1–2 days integration
4. Test message delivery across different carriers – Est. time: 4–8 hours testing

Additional Resources

Official Documentation:

• San Marino Data Protection Authority – Official regulatory body
• Twilio San Marino SMS Guidelines – Provider specifications
• Sinch API Documentation – Technical reference
• MessageBird API Reference – API documentation
• Plivo SMS API Guide – Implementation guide
• ITU San Marino Numbering Plan – Official number formatting

Community and Support:

• Twilio Community Forums: community.twilio.com
• Stack Overflow [sms] tag for technical questions
• Provider-specific support channels through account dashboards