In the first major contact between the two nations since the Iranian Revolution, U.S. President Barack Obama and Iranian president Hassan Rouhani speak on the phone -- a possible sign both are serious about reaching a pact on Iran's nuclear program.

The White House tweeted out this photo of Obama on the phone with the Rouhani, after the call.

The Twitter feed believed to be Rouhani's released this photo of the Iranian President on a plane, following his conversation with Obama.

(SOUNDBITE) (English) U.S. PRESIDENT BARACK OBAMA SAYING:

"Just now I spoke on the phone with President Rouhani of the Islamic Republic of Iran. The two of us discussed our ongoing efforts to reach an agreement over Iran's nuclear program. I reiterated to President Rouhani what I said in New York. While there will surely be obstacles to moving forward and success is by no means guaranteed I believe that we can reach a comprehensive solution."

Earlier this week, Obama hoped to meet w