You can always have talks with a player you have under contract. It's only tampering when you are talking with a player under contract with another team. See Larry Coon's Faq.
I believe you are allowed to talk to another team's player if both teams agree to it. Dwight I believe was talking to Brooklyn (and I believe LA) while still under contract with Orlando, but I believe it was because Orlando gave Brooklyn and LA permission to talk with him.