A Downing Street spokesperson said:
This evening the Prime Minister spoke to President Trump, who congratulated him on his new role.
They discussed the important relationship between our countries and the President’s successful State Visit to the UK last month.
They agreed that Brexit offers an unparalleled opportunity to strengthen the economic partnership between the UK and United States.
The leaders both expressed their commitment to delivering an ambitious free trade agreement and to starting negotiations as soon as possible after the UK leaves the EU.
The Prime Minister and the President also discussed the current tensions with Iran and the need to work together and with partners to address their destabilising behaviour in the Gulf.
They ended by looking forward to seeing each other at the G7 Summit in Biarritz next month.