There is provided rate selection methods and systems for selecting coding rates for coding frames of a speech signal to realize an average bit rate indicated by a mode. For example, a mode 0, mode 1, and a mode 2 may be defined, with each mode requiring a different average bit rate. To achieve the average bit rate of a particular mode, a coding rate is selected for each frame of the speech signal, based on the characteristics of a frame. A frame can be categorized in a class, such as noise or silence, noise-like unvoiced speech, pulse-like unvoiced speech, transition into voiced speech, unstable voiced speech, stable voiced speech. Other parameters may also be used, such as the sharpness, noise-to-signal ratio, pitch correlation, energy, and reflection coefficient. A frame may then be coded at a full-rate, a half-rate, a quarter-rate, or an eighth-rate.