Unless suppressed, a Parma Magica of sufficient level will prevent the creature from communicating with a Magus. The Mage will feel a pressure on their Parma, and will have to decide whether to suppress their Parma to allow the effect through. Without knowing that the pressure is from an attempt to communicate, most Magi would let their Parma block the effect rather than risk letting it through.
This is one of the reasons why the Order of Hermes doesn't use telepathic communication as a matter of course. How is a Mage to know if an incoming Creo Mentem effect is another Mage trying to invite them for lunch, or an enraged ghost attempting to seize control of their body?
The only difference between 5th edition and earlier editions would be how the magic resistance is resolved, the general principle would be the same. Thanks ironboundtome.
Note that Parma Magica isn't the only form of magic resistance the telepath has to worry about. Any creature with Magic, Faerie, Demonic or Divine might has Magic Resistance which might block telepathic communication. If the telepathic communication is weak enough, even just the magic resistance from an individual being in an aura might be enough to block communication, for instance someone praying at the alter of a great Cathederal.