The Havas-owned digital specialist will raise online awareness of Mobyko's website and help build a mobile social networking service.
Mobyko is a free, online back-up service for mobile phone address books, but has ambitions to grow into a social networking service.
The synchronisation software used to store personal data also allows users to download entertainment and content, such as podcasts, from different channels, so users can effectively share their content with others using the Mobyko service.
Media Contacts' remit is to capture consumers who want to secure their data in case of loss or upgrade of handset. Once this data has been captured, distribution of the Mobyko service will be strengthened by partnerships with travel, finance and entertainment content firms.