Panama City, April 10 (RHC) — Cuban President Raul Castro and U.S. President Barack Obama have spoken by phone ahead of an expected encounter at a regional summit in Panama.

The extraordinary call between the two leaders came on Wednesday, shortly before Obama departed Washington on his trip to Latin America and the Caribbean, the White House said.  Both Obama and Castro arrived in Panama City for the Summit of the Americas on Thursday evening, only minutes apart.

The two leaders have been working to restore diplomatic ties, a move that'll likely be debated at the OAS Summit in Panama.

It's only the second known conversation between the leaders of the U.S. and Cuba in more than 50 years.

The first was in December, shortly before the leaders of Cuba and the U.S. announced plans to restore diplomatic ties -- a process that is currently underway.