It is splitting the work and has appointed Fishburn on a retainer for the UK after a competitive pitch which is understood to have involved MHP as part of a small shortlist.
However, MHP has not been shortlisted in the ongoing contest for the Brussels work, which is in its final stages.
Fishburn’s brief will focus mostly on government relations and EE’s four-strong in-house public affairs team may call in other providers for one-off needs such as training.
The agency will report to EE’s director of corporate and financial affairs Dan Perlet and support the company’s focus on encouraging UK policymakers to maintain a competitive market, to lower barriers to the efficient rollout of connectivity and to support innovation.
MHP’s relationship with EE stretches back to the latter’s 2010 creation through the merger of the UK businesses of Deutsche Telekom and France Telecom, T-Mobile and Orange respectively.
MHP, which was already working for T-Mobile, won the EE account after being pitted against Orange’s agency Open Road, which now handles government relations for Vodafone.
Perlet said he had been impressed by Fishburn but expressed his thanks to MHP for its "exceptional work over the last four years and the significant contributions they have made to our business over that time".
The work included building political support for the liberalisation of the 1,800 MHz spectrum to allow for the rollout of 4G across the UK.
EE secured permission to launch its 4G services several months ahead of other operators in 2012 after the government stepped in to resolve an impasse between EE’s rivals and their regulator Ofcom about Ofcom’s decision to hand the advantage to EE.
Gavin Devine, chief executive of MHP Communications, said: "We have really enjoyed working with EE over the last four years, and we look back with huge pride on what we achieved together."
EE’s two-year relationship with FTI for corporate and financial PR is unaffected by the change and is not expected to be reviewed for some time.
The win is a coup for Fishburn’s public affairs team, which did not previously have a telecoms client, and follows it landing PRWeek’s Public Affairs Campaign of the Year award for its work for Virgin Trains on overturning the government’s decision to award the West Coast rail franchise to a rival.
However, MHP is boosting its telecoms, media and technology expertise with the recent hiring of Hanover director James Gurling, who is a previous head of public policy and government affairs at mobile operator Three.
Gurling is joining the agency next month as one of several managing directors after more than eight years with Hanover, where he led the advocacy division before being promoted to a European role last year.