Over the past couple of years, Google has taken it upon itself to help carriers develop the next generation of SMS known as Rich Communication Services, or just RCS. Of course, for RCS to work across carriers and across borders, each individual carrier must decide carrier interoperability and which devices are compatible. The reality is there are carrier politics and rules that have made progress on RCS slow to a crawl. As first reported by The Verge Google is now making the final push for RCS to become a useful reality. Android users in the UK and France will be able to opt-in to use RCS...
Source: https://www.gsmarena.com/google_will_offer_optin_rcs_regardless_of_carrier_available_in_uk_coming_to_france-news-37623.php