Orange and O2 lost a quarter of their frequencies in the 2100 MHz band. 4ka gained access to it for the first time, and its customers lost a simple way to choose their network

As of Tuesday, September 8, Slovak mobile operators have a differently divided 2100 MHz frequency band. Slovak Telekom retained 2×20 MHz in it, Orange and O2 dropped to 2×15 MHz, and 4ka, which previously had nothing in this band, received 2×10 MHz. This is a change stemming from last year's frequency auction, most of which will only take effect in 2029. DSL.sk ↗

How the Band Was Redivided

The number 2100 MHz denotes a band, that is, a section of the radio spectrum, and the figure 2×15 MHz indicates how wide a chunk of it an operator received. The "2×" in the notation means it consists of two separate sections of equal width, one for downloading data and the other for uploading. In this band, operators have a total of 2×60 MHz. Until now, the three largest operators split it equally at 2×20 MHz each, and Swan, which operates 4ka, did not have a single megahertz there. As of Tuesday, Slovak Telekom continues to hold 2×20 MHz, Orange and O2 each hold 2×15 MHz, and 4ka holds 2×10 MHz. DSL.sk ↗

Both Orange and O2 thus lost a quarter of their width in this band. This is not a band that determines territorial coverage; rather, it serves capacity in more densely populated areas, where it is shared among all connected users at once. How the narrowing will affect actual speeds depends on how the operator makes use of the spectrum, and this has not been disclosed.

Why This Is Happening Now

The change is the delayed result of an auction that the Úrad pre reguláciu elektronických komunikácií a poštových služieb (Office for the Regulation of Electronic Communications and Postal Services) concluded on Wednesday, July 9, 2025, and described as the largest electronic auction of mobile frequencies in Slovakia's history. The 800, 900, 1500, 2100 and 2600 MHz bands were auctioned, and all the frequencies on offer were sold. SITA ↗

The operators committed to paying more than 506 million euros for the frequencies, in installments through 2028. DSL.sk ↗

According to the Office, the record proceeds exceeded expectations by roughly 140 million euros. It attached a warning to the result. "On the one hand, we are pleased that the record proceeds will help consolidate the state budget; on the other hand, a price for the purchase of frequencies that is too high by European standards may slow operators' investment plans for the development of digital services and innovation," the Office stated. It thus itself admitted that the price it had secured through the auction could slow investment in networks. SITA ↗

Operators will gain access to most of the auctioned frequencies only from January 1, 2029, and will hold them until the end of 2048. The 1500 MHz band was available immediately after the auction, and the 2100 MHz band was freed up precisely on September 8, 2026, because older licenses had been in effect until then. Tuesday's change is therefore not a new decision, just a date that had been known for more than a year. SITA ↗

What 4ka Did Not Gain in the Auction

For 4ka, ten megahertz in the 2100 MHz band is a significant addition. However, in the bands that matter most for territorial coverage, it came out of the auction with the smallest allocation. In the 800 MHz band, which propagates best and allows large areas to be covered with fewer transmitters, Slovak Telekom, Orange and O2 each obtained 2×10 MHz for between 69.7 and 71.4 million euros. Swan gained nothing in this band. In the 900 MHz band, which has a similar property, the three largest operators each received 2×10 MHz and Swan received 2×5 MHz, though it will only be able to use this from 2029. DSL.sk ↗

Limited access to frequencies below one gigahertz is one of the reasons why 4ka has long had the smallest own coverage and why the agreement with Orange is key for it. It operates its own 4G and 2G network mainly in the 1800 MHz band, of which, following the 2022 redistribution, it has 20 MHz across most of the territory and 15 MHz across a large part of western Slovakia. Part of it must be reserved for the older 2G network. For now, it is building its 5G network mainly in the 3500 MHz band, which has a short range and, according to DSL.sk, can realistically only be used in cities. DSL.sk ↗

The Change 4ka's Customers Felt

On the very same day the band was redistributed, Orange and Swan announced an extension of their national roaming agreement. This is an arrangement in which a smaller operator's customer connects to the larger operator's network. 4ka's customers will thus be able to use part of Orange's network until at least the end of 2028, that is, for more than another two years. The technical conditions are changing, however. According to Orange, the scope and quality of national roaming are to remain at least at their current level. Živé.sk ↗

The essence of the change is that 4ka's customers no longer use Orange's network in the 2100 MHz band while roaming, but in the 1800 MHz band instead. Orange describes this as a benefit. "The new 1,800 MHz frequency will also be used across the whole territory of Slovakia at available capacity. The 1,800 MHz band, which 4ka's customers will now also use as part of national roaming, brings higher capacity for mobile data services," the operator stated. A lower frequency also generally propagates over a greater distance and penetrates buildings better. Živé.sk ↗

The website DSL.sk noticed the changes as early as September 3, that is, several days before the announcement, based on experience from multiple locations. Exactly when all customers switched to the new state is not documented. DSL.sk also points to a consequence that has nothing to do with speed or range: 4ka also operates its own network in the 1800 MHz band, so the two networks now overlap in this band. The operator and the website are thus each talking about a different aspect of the same change. DSL.sk ↗

Why the Networks Cannot Be Easily Told Apart

Until now, telling the networks apart was only possible through a workaround. Since the beginning of 2024, when Orange switched off its 3G network and roaming moved to 4G, its base stations have announced themselves to 4ka's customers as 4ka stations. The phone therefore cannot tell whose network it is currently using, and the user cannot influence this either by turning data roaming on or off or by choosing a technology, since both networks are 4G. The only remaining guide was the frequency band, which can be manually restricted on phones and especially on data modems. As long as Orange made the 900 and 2100 MHz bands available and 4ka transmitted in the 1800 MHz band, it was possible to set which network the customer wanted to use. DSL.sk ↗

Since both networks now overlap in the 1800 MHz band, this guide has disappeared for ordinary devices. Technically, the networks still differ by channel number, but most devices do not offer such a choice. A minor exception remains 4ka's own 5G network, though it still has limited coverage. Moreover, according to DSL.sk, the 900 MHz band is not made available across the whole territory, so in places without it, the opposite choice — that is, exclusively Orange's network — cannot be forced either. DSL.sk ↗

This matters in two situations. The first is ordinary connectivity, when the device automatically prefers the network that happens to be slower at a given place and time, and the user no longer has any way to override it. The second is data-heavy plans, for example ones with 300 gigabytes a month. Data transferred over Orange's network is subject to a limit known as FUP, that is, fair use policy rules. If it is used up before the customer actually needed Orange's network, according to DSL.sk they may be left dependent on 4ka's weaker coverage for the rest of the billing period. In the worse case, they remain connected to Orange's network, are unable to switch, and their data speed drops to 256 kilobits per second. The operators have not disclosed the size of this limit or how many customers it affects. DSL.sk ↗

What Remains Open

4ka has not yet announced when or how it will use the new frequencies. According to DSL.sk's testing at several base stations in western Slovakia, it did not switch them on right away. The new band could serve either capacity or coverage; the operator has not stated how it will be used. For its 5G network, 4ka expects this year to increase coverage from 53.5 percent of the population in mid-May to 59 to 60 percent by the end of the year. DSL.sk ↗

It also remains an open question whether the two changes are related. DSL.sk allows for the possibility that, in some locations, Orange might for now operate a 4G network on 4ka's new frequencies as part of the expanded roaming agreement, or that these frequencies could also be made available to its own customers. Neither operator, however, has announced or confirmed this, and according to the website, neither responded to its questions about the roaming changes. This is therefore a hypothesis, not a documented plan. DSL.sk ↗

Moreover, cooperation between the two operators may not end with roaming — according to Živé.sk, they are also negotiating the sharing of mobile infrastructure. Živé.sk ↗

The rest of the auction will only take effect in more than two years. From January 2029, the 800, 900 and 2600 MHz bands will be freed up — including those that determine coverage outside cities. Only then will what the operators bought in the auction in the summer of 2025 fully take effect. SITA ↗