Jesus spoke with Elijah and Moses at the Transfiguration.
Mark 9:2-13 New International Version (NIV)
And you thought that answered my question? Seriously? May I remind you that not only was Jesus already in His glorified body (which the apostles were not) but He was also God. Not once in all of scripture is communication with departed souls condoned.
c n kRa
Mark 9:2-13 New International Version (NIV)
The Transfiguration
2 After six days Jesus took Peter, James and John with him and led them up a high mountain, where they were all alone. There he was transfigured before them. 3 His clothes became dazzling white, whiter than anyone in the world could bleach them. 4 And there appeared before them Elijah and Moses, who were talking with Jesus.
5 Peter said to Jesus, “Rabbi, it is good for us to be here. Let us put up three shelters—one for you, one for Moses and one for Elijah.” 6 (He did not know what to say, they were so frightened.)
7 Then a cloud appeared and covered them, and a voice came from the cloud: “This is my Son, whom I love. Listen to him!”
8 Suddenly, when they looked around, they no longer saw anyone with them except Jesus.
The text FAILS to say from whence M&E came from; neither where they went...
Jesus could do so because he is God incarnate. The disciples weren't allowed to because the were not God incarnate.
When you are God incarnate you can do whatever you want. Until then you should love, serve and obey the Lord.