8. A content filtering system comprising: a server computer comprising a dictionary that comprises a plurality of dictionary words, a word segmentation module configured to detect occurrences of dictionary words in a plurality of training text messages, a feature selection module configured to select feature words from among dictionary words occurring in the plurality of training text messages and to generate a feature list that is a subset of the dictionary and comprising the feature words, a first conversion module configured to convert the plurality of training text messages into vectors having numeric representations of selected words as items, and a training module configured generate a learning model; and a mobile phone configured to receive the feature list and the learning model, the mobile phone comprising a second conversion module configured to detect occurrences of feature words from the feature list in an incoming text message and to convert the incoming text message into an input vector having numeric representations of feature words occurring in the incoming text message as items, the feature words occurring in the incoming text message having associated statistical values that are used as a parameter in converting the incoming text message into the input vector, the statistical values being pre-computed prior to being received in the mobile phone, and a prediction module configured to determine a classification of the incoming text message based on a comparison of the input vector to the learning model.
10. The system of claim 8 wherein the incoming text message comprises an SMS text message.