I'm with sky and calls/text/data to/from/in the Isle of man are all included in my mobile contract, most of the main providers offer the same

Some years ago the EU made roaming in the European Union free, as the Isle of Man was not part of the EU, mobile providers started charging for calls, etc to and from the Isle of Man

Once the UK left the EU most mobile providers made calls, etc part of your contract - so check your contract

I have no idea what the charges are for pay as you go phones as I've never had one