This type of roaming concerns the possibility of switching to the network of a foreign service provider. It is therefore of particular interest to international tourists and business travelers. Overall, international roaming is the easiest with the GSM standard, since it is used by more than 80% of mobile operators worldwide. But even then there may be problems because countries have allocated different frequency bands for GSM communications (there are two groups of countries: most countries use 900/1800 MHz, but the United States and other countries of America have allocated 850/1900 MHz): for a phone to work in a country with a different frequency allocation, it must support one or both frequencies of this country and therefore be tri-or quad. While international roaming allows the traveller to stay in touch during their trip, it can also entail significant costs for users. Indeed, the use of mobile networks outside the country of origin can lead to significant billing on the part of the mobile operator of origin.  This type refers to the ability to switch from one mobile operator to another in the same country. For example, a T-Mobile USA subscriber, authorized to travel on the at > T Mobility service, would have national roaming rights. For commercial and licensing reasons, this type of roaming is only allowed in specific circumstances and under the control of the authorities. This is often the case when a new entity has been awarded a mobile phone licence in order to create a more competitive market by offering the new entrant coverage comparable to that of incumbents (by requiring existing operators to allow roaming while the new entrant has time to set up its own network). In the European Union, the regulation of roaming charges began on 30 June 2007, requiring service providers to reduce their roaming charges across the entire 28-member bloc. Subsequently, the EEA Member States were also part of it. The regulation set a price cap of €0.39 (€0.49 in 2007, €0.46 in 2008, €0.43 in 2009) per minute for outgoing calls and €0.15 (€0.24 in 2007, €0.22 in 2008, €0.19 in 2009) per minute for incoming calls excluding taxes. After finding that market conditions did not justify lifting the restriction on roaming within the EEA, the Commission replaced the 2012 Law. Under the 2012 Regulations, retail roaming limit rates expired in 2017 and wholesale cap rates expire in 2022. In mid-2009, this regulation also included a maximum price of €0.11 (excluding taxes) for SMS. Although these user/network scenarios focus on roaming from GSM network operator networks, roaming can be clearly bidirectional, i.e. from public Wi-Fi operators to GSM networks. Traditional roaming on networks of the same standards, for example, a Wi-Fi network or a GSM network, has already been described above and is also defined by the strangeness of the network depending on the type of registration of participants in the participant register. Every time you cross a border within the EU, you should receive an SMS from your mobile operator to inform you that you are roaming and remind you of their fair use policy. The legal aspects related to roaming negotiated between roaming partners for the billing of the services provided are generally defined in so-called roaming agreements. The GSM Association sets out the content of these roaming agreements in a standardised form for its members. .