Murphy joined in April 2008 from Superdrug, where he had been group marketing director for three years. He replaced Mark Horgan, who moved to a European role that was subsequently made redundant.
Murphy attempted to reposition the brand with a series of SMS services including sports scores, weather updates and answers to trivia questions.
To support the repositioning, the company launched a TV campaign, created by The Brooklyn Brothers, featuring animated versions of the 118 118 runner brand characters.
Murphy hired ZenithOptimedia to handle the brand's consolidated £14m media business and handed its digital account to Work Club.
A spokesman for The Number 118 118 said Murphy had completed his contract.