@EU_Commission "Their messaging apps will have to interoperate with others."

Does that mean that if I have, lets say, Signal, would I be able to text people on WhatsApp?

Because "their messaging apps" is clear. But the "others" is a bit vague, unspecified.

And 6 months to implement that... I dream of that happening, but I doubt they would do in such a short time.
What will happen if they don't? Fines?