Firstly, don't look at this large potential audience as a group to which you can simply broadcast. Spam is not what we're talking about here, instead create a dialogue. This is a direct medium, so try to communicate with users one at a time or in small groups. As an example, last July, Coca-Cola invited participants to enter a contest to guess the next day's temperature in Beijing. The 'invitation' was communicated through Coke's existing advertising channels, so users could choose to individually opt-in. Four million messages were generated during the 40-day promotion.
Try to create a service or experience and not simply a direct marketing message. Interactivity with a brand has repeatedly been proven to increase awareness and recall so make whatever experience fun to interact with.
To create buzz around the launch of the Spiderman movie, Sony Pictures created a wireless game. Once opted-in, users could invite friends to play or be assigned a partner. Players could chat with each other after each game session, creating an 'interactive experience' for each user.
A typical mobile campaign in China is based around SMS services since 95 plus per cent of phones here are SMS-capable (MMS with full colour is sexy, but penetration is still low). This allows you just 70 characters per screen (160 in English) but don't despair since if you focus on compelling services and write tight copy this is sufficient.
To kick off a mobile campaign, you will need to work with a mobile marketing agency or wireless value-added service provider that has a short code with coverage in the provinces required and experience in creating compelling SMS applications.
Most campaigns are 'self-liquidating' in that users who opt-in pay a nominal per message fee (RMB0.1 to send and anywhere from RMB0.1 or up to receive) in exchange for winning a prize. For instance, in the Coke campaign, users stood to win a year's supply of Coke or a Siemens phone and those who didn't win could download a free Coke jingle.
Some ideas: Ask users to take a fun personality profile test. Give them some compelling, funny and insightful results but also use it to tell them which of your product lines they are most suited for. Or, turn your packaging into a lottery ticket. Print a unique code on the pack and let users 'Txt n' Win' through their phones to see if they've won. Non-winners get a second chance through a mobile quiz or get asked to opt-in to receive future promos.