Phone Numbers in Slovakia: A Comprehensive Guide

Quick Reference

• Country: Slovakia
• Country Code: +421
• International Prefix: 00
• National Prefix: 0
• Regulatory Body: Regulatory Authority for Electronic Communications and Postal Services (RÚ)

Overview

This guide offers an in-depth look at Slovakia's telephone numbering system, covering number formats, dialing procedures, and regulatory details. It is tailored for telecom professionals, developers, and systems administrators who need to understand Slovak phone numbers thoroughly.

Number Formats

General Structure

Slovak phone numbers have a fixed-length format based on the service type. The structure includes the country code (+421), followed by an area code or prefix, and the subscriber number.

• Country Code: +421
• Area Code/Prefix: 1-2 digits (varies by region or service)
• Subscriber Number: 6-8 digits

Geographic Numbers

Geographic numbers are specific to Slovak regions and typically have a 2-digit area code.

Mobile Numbers

Slovak mobile numbers start with 9 and are 9 digits long.

Regular Expression for Mobile Numbers:

^\+4219\d{8}$

Toll-Free Numbers

Toll-free numbers in Slovakia begin with 800 and are 9 digits long.

Premium Rate Numbers

Premium rate numbers start with 90X and are 9 digits long, often used for services with additional charges.

Shared Cost Numbers

Shared cost numbers start with 85X-89X and are 9 digits long, splitting costs between caller and provider.

Dialing Procedures

Domestic Calls

• Landline to Landline: Dial area code + subscriber number. E.g., 02 123 4567 for Bratislava.
• Landline to Mobile: Dial mobile prefix + subscriber number. E.g., 0903 456 789.
• Mobile to Mobile: Dial mobile prefix + subscriber number. E.g., 0903 456 789.

International Calls

• Outgoing: Dial 00 + country code + area code (if applicable) + subscriber number. E.g., 00 44 20 7946 0958 for London, UK.
• Incoming: Replace leading 0 with +421 when dialing into Slovakia. E.g., +421 2 123 4567.

Number Portability

Slovakia supports mobile number portability (MNP), allowing users to keep their numbers when switching providers. This is regulated by the Regulatory Authority for Electronic Communications and Postal Services (RÚ).

Major Telecom Operators and Number Ranges

Major Telecom Operators

1. Slovak Telekom
2. Orange Slovakia
3. O2 Slovakia
4. 4ka (SWAN Mobile)

Number Ranges

ITU-T Recommendations/Standards

Slovakia complies with the ITU-T E.164 standard for telephone numbering, allowing a maximum of 15 digits for international numbers, including the country code.

Number Allocation and Management

The Regulatory Authority for Electronic Communications and Postal Services (RÚ) oversees the allocation and management of phone numbers in Slovakia, including number range assignments and portability regulations.

Technical Restrictions and Special Cases

• Golden Numbers: Memorable numbers with repeating digits may be sold at a premium.
• Number Blocking: Users can block specific numbers through their provider for security or privacy.

Technical Considerations for Developers

When developing systems for Slovak phone numbers, consider:

• Validation: Use regex to validate numbers based on provided formats.
• Normalization: Remove non-numeric characters (except + in international formats) before processing.
• Portability: Ensure systems handle number portability, especially for mobile numbers.
• Length Constraints: Enforce strict length constraints based on number type (e.g., 9 digits for mobile).