Area Code 604 – Mobile Network
The phone area code for Mobile Network is 604 (international format +420604). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 604
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Overview of Czech Mobile Prefix 604
The prefix +420 604 is a non-geographic mobile network code assigned within the Czech Republic's national numbering plan. As per ITU-T E.164, the full international number format is +420 604 XXX XXX, comprising the country code (+420), the mobile network prefix (604), and a seven-digit subscriber number. This prefix is not tied to any specific geographic region; it is used exclusively for mobile services, enabling nationwide coverage and number portability.
Technical Allocation and Routing
The Czech Telecommunication Office (ČTÚ) allocates mobile prefixes to licensed Mobile Network Operators (MNOs) and Mobile Virtual Network Operators (MVNOs). The 604 prefix is currently utilized by a major MNO, supporting GSM, UMTS, LTE, and 5G services. Calls to numbers beginning with 604 are routed via the home network's HLR (Home Location Register) to the subscriber's current location, whether within Czechia or roaming internationally. SMS and MMS messages are delivered using standard SMSC protocols, and the prefix does not affect message content or routing beyond initial identification.
Dialing Formats and Caller Instructions
Within the Czech Republic, callers must dial the national significant number (NSN) in the format 604 XXX XXX (without the leading +420). For international callers, the format is +420 604 XXX XXX or 00420 604 XXX XXX from countries using the international prefix 00. When dialing from a foreign country, the leading '0' in the national prefix is omitted; hence, the number starts with +420 followed by 604. For example, a Prague-based caller would dial 604 123 456, while a caller from Germany would dial 00420 604 123 456.
Number Portability and Regulatory Aspects
Mobile number portability (MNP) is fully implemented in Czechia. Subscribers may retain their 604 numbers when switching operators, meaning that the prefix does not guarantee the current operator. However, the prefix remains non-geographic and does not affect tariff structures, which are determined by the subscriber's chosen plan. The Czech regulator mandates that all mobile numbers, including 604, must support equal access to emergency services (112) and be reachable from all networks without discrimination.
Usage and Market Context
The 604 prefix is widely used for personal and business mobile lines. As of 2024, it represents a significant portion of the country's mobile subscriber base. Businesses often use 604 numbers for customer contact, and the prefix is recognized as a standard mobile identifier. There are no special restrictions on VoIP or OTT services; however, such services may require additional verification to ensure correct routing. For enterprises, using a 604 number can enhance credibility, as it is a recognized mobile prefix, and it supports SMS-based two-factor authentication (2FA) and other value-added services.