Pre trial mediation from palisades collection llc

I was recently sen a summone form court to appear in a pre trial mediation from palisades collection llc . It was claimed that I owed money for a At&t account. Before going to the mediation I sent certified letters asking to validate the dept. I got no response and when I went to the mediation I asked again for validation and got nothing and it was set for trial. I againg sent certified letters to both palisades and there attorneys and got no response. I week later I got a letter of voluntary dismissal without prejudice. I do not know what this means execpt that I dont have to go to court. Is there any more to this and what should I do to get this off my credit report.