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Slovakia SMS Best Practices, Compliance, and Features
Slovakia SMS Market Overview
Locale name:
Slovakia
ISO code:
SK
Region
Europe
Mobile country code (MCC)
231
Dialing Code
+421
Market Conditions: Slovakia has a mature mobile market with high SMS adoption rates. The country's telecommunications sector is served by major operators including Orange Slovakia, Slovak Telekom, and O2 Slovakia. While OTT messaging apps like WhatsApp and Facebook Messenger are popular, SMS remains a crucial channel for business communications, particularly for authentication and notifications. The market shows a relatively even split between Android and iOS devices, with Android having a slight edge in market share.
Key SMS Features and Capabilities in Slovakia
Slovakia supports most standard SMS features including concatenated messages and alphanumeric sender IDs, though two-way SMS functionality is limited.
Two-way SMS Support
Two-way SMS is not supported in Slovakia through most major SMS providers. This means businesses cannot receive replies to their messages through standard SMS APIs.
Concatenated Messages (Segmented SMS)
Support: Yes, concatenation is supported for messages exceeding standard length limits. Message length rules: Standard SMS length is 160 characters for GSM-7 encoding, or 70 characters for Unicode (UCS-2). Encoding considerations: Messages using GSM-7 encoding can be concatenated up to 153 characters per segment, while UCS-2 encoded messages allow 67 characters per segment.
MMS Support
MMS messages are automatically converted to SMS with an embedded URL link. This ensures compatibility across all devices while still allowing rich media content to be shared through a web interface.
Recipient Phone Number Compatibility
Number Portability
Number portability is available in Slovakia, allowing users to keep their phone numbers when switching carriers. This feature is fully supported and does not affect message delivery or routing.
Sending SMS to Landlines
Sending SMS to landline numbers is not supported in Slovakia. Attempts to send messages to landline numbers will result in delivery failure and may trigger error responses from the SMS API (e.g., error code 21614 for some providers).
Compliance and Regulatory Guidelines for SMS in Slovakia
As a member of the European Union, Slovakia follows GDPR and e-Privacy Directive requirements for SMS communications. The primary regulatory authority is the Office for Personal Data Protection of the Slovak Republic (Úrad na ochranu osobných údajov Slovenskej republiky).
Consent and Opt-In
Explicit Consent Requirements:
Written or electronic consent must be obtained before sending marketing messages
Consent must be freely given, specific, informed, and unambiguous
Keep detailed records of when and how consent was obtained
Purpose of messaging must be clearly stated during opt-in
HELP/STOP and Other Commands
All marketing messages must include clear opt-out instructions
STOP command must be supported in both Slovak and English
Common Slovak keywords include:
STOP or ZASTAVIT for opt-out
POMOC or HELP for assistance
Messages should be processed in both upper and lower case
Do Not Call / Do Not Disturb Registries
Slovakia does not maintain a centralized Do Not Call registry. However, businesses must:
Maintain their own suppression lists
Honor opt-out requests within 24 hours
Keep records of opted-out numbers for at least 2 years
Regularly clean contact lists to remove unsubscribed numbers
Time Zone Sensitivity
Slovakia observes Central European Time (CET/CEST). While there are no strict legal restrictions on SMS timing:
Avoid sending messages between 20:00 and 08:00 local time
Respect weekends and national holidays
Emergency notifications are exempt from time restrictions
Phone Numbers Options and SMS Sender Types for in Slovakia
Alphanumeric Sender ID
Operator network capability: Fully supported Registration requirements: No pre-registration required, dynamic usage allowed Sender ID preservation: Sender IDs are preserved and displayed as-is to recipients
Long Codes
Domestic vs. International:
Domestic long codes not supported
International long codes supported but sender ID may be modified
Sender ID preservation: International long code sender IDs are typically replaced with generic alphanumeric IDs Provisioning time: Immediate activation Use cases: Transactional messaging, alerts, and notifications
Short Codes
Support: Not currently supported in Slovakia Provisioning time: N/A Use cases: N/A
Restricted SMS Content, Industries, and Use Cases
Restricted Industries and Content:
Gambling and betting services (unless properly licensed)
Adult content or services
Cryptocurrency promotions
Unauthorized financial services
Political campaigning without proper disclaimers
Content Filtering
Known Carrier Filtering Rules:
Messages containing certain keywords may be blocked
URLs should be from reputable domains
Avoid excessive capitalization and special characters
Best Practices to Avoid Filtering:
Use clear, professional language
Avoid URL shorteners
Include company name in message
Maintain consistent sending patterns
Best Practices for Sending SMS in Slovakia
Messaging Strategy
Keep messages under 160 characters when possible
Include clear call-to-action
Use personalization tokens (recipient's name, relevant details)
Maintain consistent brand voice
Sending Frequency and Timing
Limit to 2-4 messages per month per recipient
Respect Slovak holidays and cultural events
Send during business hours (9:00-17:00)
Space out bulk campaigns to avoid network congestion
Localization
Primary language should be Slovak
Consider including English for international audiences
Use proper diacritical marks in Slovak text
Respect local date formats (DD.MM.YYYY)
Opt-Out Management
Process opt-outs in real-time
Maintain centralized opt-out database
Confirm opt-out with one final message
Regular audit of opt-out list
Testing and Monitoring
Test across all major Slovak carriers
Monitor delivery rates by carrier
Track engagement metrics
Regular A/B testing of message content
SMS API integrations for Slovakia
Twilio
Twilio provides robust SMS capabilities for Slovakia through their REST API. Authentication uses account SID and auth token credentials.
import{ Twilio }from'twilio';// Initialize client with your credentialsconst client =newTwilio( process.env.TWILIO_ACCOUNT_SID, process.env.TWILIO_AUTH_TOKEN);// Function to send SMS to SlovakiaasyncfunctionsendSlovakiaSMS( to:string, message:string, senderId:string){try{// Ensure number is in E.164 format for Slovakia (+421)const formattedNumber = to.startsWith('+421')? to :`+421${to}`;const response =await client.messages.create({ body: message, from: senderId,// Alphanumeric sender ID to: formattedNumber,});console.log(`Message sent successfully! SID: ${response.sid}`);return response;}catch(error){console.error('Error sending message:', error);throw error;}}
Sinch
Sinch offers SMS API access with service plan ID and API token authentication.