The soul now exists in an astral body. Which is appropriate for the astral realm. The light body spirit still has feelings for loved ones left behind and still is able to think. For the spirit entity to connect to an medium all they have to do is merge the aura of the medium and connect their mental field to mine. Now a mind to mind communication takes place.
Symbolism is the language of the universe.
The disincarnate spirit will impress a message of symbols through their mental field to the medium's mental field. The medium will often hear a combination of words, see images, and feel impressions from the disincarnate spirit. Usually the first thing the spirit will tell the medium is their name. If they had an unusual name, they might try spelling it. One young girl in spirit named Robin who was killed in a car accident comes in with that song.