This piece of news comes straight from AlternativeNation.net

Guns N’ Roses frontman Axl Rose revealed in a new Brazilian television interview how he and Slash came to play together again. The interview was filmed before GNR’s show in Orlando. Axl recalled asking Fernando, a member of his management team Team Brazil, for Slash’s phone number.
It had a lot to do with Paul Tollet of Coachella. He started talking about it, it seemed real, so at that point, I just told my people that they could go ahead and start talking to people, and see what’s going on. As it became more real, I texted Fernando and asked for Slash’s number. Then Fernando texts his Mom and is like: ‘If this is a joke, I’m going to kill you.’”
Slash was on tour so it took some time to the meeting. Slash and Axl finally met in October 2015.
“I called Slash but he was on tour or something so we’ve only met in person last October when he came to dinner at my house. Later Duff joined us and we went to work.”
He also discussed how the tour came to be.
“It started with talking about Coachella, but at the same time as those talks were starting, there were people involved with Coachella and agencies and things, so they were having these conversations.”
“We [all] started talking in the spring [about touring], everybody’s people were finding out about possibilities and things like that, and we started talking together in the spring [about touring].”
He also discussed original members Steven Adler and Izzy Stradlin not being part of Guns N’ Roses’ reunion. He said that Steven is not 100% because of his back surgery, despite making guest appearances, and they could not count on Izzy because if they decide to do anything, they don´t know if Izzy will be there or not.
“Steven has played with us but he isn’t 100%, he’s had back surgery. And Izzy… I dont even know what to say, we make arrangements and then he goes and does other things. With Izzy you never know what to expect.