Bell Pottinger Public Affairs will develop and run a strategic PA programme.
It will also provide PA support around the Communications Bill, which is set to become law next year and will create communications super-regulator Ofcom.
BPPA managing director Peter Bingle heads a four-strong account team, reporting to mmO2 head of PA Richard Brown.
'There's a very wide public policy agenda. We have to work out what the priorities are in the short term and then build an ongoing programme,' said Bingle.
mmO2 owns mobile networks in four countries: the UK, Germany, Holland and Ireland. The group, which last year demerged from former parent BT, also has operations on the Isle of Man and mobile internet portal firm Genie.