The party warlock recently acquired a ring of mind shielding in Tales from the Yawning Portal
The party patron is a spellcaster who is in a city distant from them. She is about to contact them via the spell Dream for an update on their progress in resolving the mission she has set them upon, and does not know about the ring. She wants a much longer conversation than sending would allow, but has not used dream before to contact them and they do not know that she is planning to do so.
Dream is a 5th level illusion spell, and will allow her to contact the party as follows:
If the target is asleep, the messenger appears in the target’s dreams and can converse with the target as long as it remains asleep, through the duration of the spell.
Note that the contact is automatic and there is no saving throw, so long as she does not use the spell to attack the target with a nightmare.
The ring says that
Creatures can telepathically communicate with you only if you allow it.
Will the ring protect against the automatic contact from the spell?
If the warlock can use the ring to decide whether or not to ‘receive the call’ while he sleeps, will he know who the sender is, or who the sender is purporting to be, before he makes this decision?
For me, the answer hinges on how I should understand "telepathically" in this description, as the natural English meaning of ‘communicating feeling at a distance’ which could include the Dream spell, or as a specific term that applies only to abilities specifically using the word telepathy, such as various feats, spells, and creature languages. Thus, an answer able to clarify this would be particularly helpful to me. However, any answer that resolves the question is welcome.
Related: Is the Telepathy rule in the Monster Manual only applicable to monster telepathy abilities?