This article is from the Dissociation FAQ, by Discord (email@example.com) with numerous contributions by others.
Sometimes it's through what would be speech if it were outside the body;
telepathy might be a reasonable word for it....one hears the words the
other alter speaks.
Sometimes it's through a sort of telepathy without words--you just know
what the other alter is trying to convey. This can either only happen
when the alter wishes to communicate things or happen when you wish to
find things out ("mind-reading" of a sort).
Sometimes this mind-reading/telepathy is accompanied by insight into the
alter's feelings (empathy). Some alters communicate solely through
Sometimes the various alters take turns controlling the body so as to
Sometimes it's a mix of all of this.
In the case of "mind-reading" and "empathy", sometimes it is not possible
to shut out the alters thoughts or feelings when communicating with them.
Feelings sometimes "bleed over" into the various alters communicating.
Some systems teach the various alters how to shield their feelings and
thoughts from other alters so that communication is strictly deliberate.