The move by the mobile phone brand has emerged in the same month that FD-LLM chairman David Cracknell announced he was quitting the agency.
Cracknell has yet to announce his next move.
The loss of the Orange account is a fresh blow for FD-LLM which has made a concerted effort to improve its standing after losing a number of key staff in the past year.
Orange has appointed Open Road to handle the full range of public affairs activities, after using FD-LLM for ten years.
Orange did not under-take a formal pitch process for the account but spoke to those agencies that had contacted them proactively.
Head of government policy and mobile regulation Simon Grossman said that Orange chose Open Road so that they would get 'a more personal responsive type of approach'.
'One of the things they will be doing is increasing the profile of our new chief executive Tom Alexander,' Grossman said.
'Open Road will also be working on regulation issues, to promote the fact that the mobile industry is a competitive market so there is no need for increased regulation,' he added.