Is roaming free in the Isle of Man if our group uses our regular UK (O2, EE, Vodafone) or EU SIM cards?

No, this is a common misconception and a major roaming trap! Even though the Isle of Man is a British Crown Dependency, it is not considered part of the UK for mobile roaming purposes, nor is it in the European Union. This means 'Roam Like at Home' benefits and standard UK carrier plans (like O2, EE, or Vodafone) do not apply. Your group will incur significant roaming charges if you rely on your domestic SIMs, making Triply a much smarter and more affordable choice.