The new rules apply to any member of the EU and, later on, the European Economic Area (EEA) which includes Norway, Iceland and Liechtenstein.
Under the ‘roam at home' agreement, customers with a mobile phone contract in these countries will be charged the same for texts, calls and data when abroad within the EU as they are in their home country.
Not being a member of either the EU or EEA, Switzerland is not a part of the new agreement.
Despite that, some foreign mobile phone companies are extending their roaming-free zone to Switzerland.
British customers of O2 and Three, for example, can use their phones in Switzerland on their normal tariff with no extra charge. As can French customers of Orange and Spanish customers of Vodafone.
But it doesn't work the other way around, with customers of Swiss operators still having to fork out high prices to get a deal including roaming for their handy/natel (as a mobile phone is known in Swiss German and French).
Salt charges 89 francs a month for a subscription that includes unlimited roaming in the EU, versus 39 francs a month for a Switzerland-only deal.
Sunrise charges 100 francs for a similar roaming deal under its ‘Freedom' range, and offers add-on roaming bundles for pay-as-you-go travellers.
Swisscom offers subscriptions that include roaming in 190 countries starting from 60 francs a month for 30 days up to a whopping 180 francs a month for unlimited roaming.
Outside monthly deals, pay per text/minute/megabyte prices are also high. For example a Sunrise customer roaming in France would pay 1.10 francs a minute for a local call, 1.30 francs to call Switzerland, 50 centimes to send a text and one franc per megabyte of data, as well as charges to receive calls and texts.
Some in Switzerland fear that the new division between Switzerland and the rest of Europe could be detrimental to Switzerland's tourism industry.
And back in May Swiss MP Elisabeth Schneider-Schneiter said she felt the Swiss government should discuss the issue to ensure Swiss phone users are not discriminated against.
“If the EU can stop roaming then it must be possible for Switzerland,” she said.
But a spokesman for online comparison site Comparis.ch told Swiss media at the time that roaming charges were a lucrative business for Swiss companies, so they had “little interest” in joining the EU deal.