Ofcom faces criticism for allegedly stalling on its proposed ban.
Bodies such as consumer watchdog Which? and the National Consumer Council accused the regulator of failing to address childhood obesity after Ofcom announced a fresh round of consultation on its proposals in March.
Ofcom is also preparing to take an awareness-raising lead as the UK prepares for analogue broadcast switch-off. Other issues for the body include the forthcoming auction of radio spectrum for use in mobile and wireless telecoms. A similar auction in 2000 for 3G licences raised £22bn for the Treasury.
Rossiter is replaced by comms manager Ed Knight, whose responsibilities include promotion of Ofcom's work within the European Community, notably its chairing of the European Regulatory Group.
Both men have worked at Ofcom since the body's inception in 2003.