Methods and systems for decoding monitored communication signals using previously identified side information. Information, which is used for decoding a given frame and is provided to the decoder not via the main communication channel between a base station and a mobile station, is referred to herein as “side information.” The side information can also be viewed as extrinsic information that was derived during previous decoding operations. The monitoring system holds, for certain frames, a-priori information of one or more data values that are expected in these frames. Decoding using this a-priori information enables an Error Correcting Code decoder to successfully decode such frames, which would otherwise fail to decode.