This paper presents a new structure of an Acoustic Echo Canceller (AEC) designed to operate in the Mobile Switching Center (MSC) of a GSM network. The purpose of such system is to cancel the echo for all the subscribers. Contrarily to the conventional AEC, the proposed combined AEC/CELP Predictor is able to take into account the non linearities introduced by the GSM speech coders/decoders. A short term predictor is used to model the behavior of the codecs. This new combined system presents higher performance compared to the conventional AEC.