Method for supporting multiple registration from the same user requested from different terminals in a telecommunications system requiring to manage information related to the location of said user and related to the plurality of identifiers that identify said user in said system. The enrollment and test speech are both subjected to a feature extraction process to derive fixed-length feature vectors, and the feature vectors are compared, using a linear discriminant analysis and having no dependence upon the order of the words spoken or the speaking rate. The authenticating device may be a personalized device, such as a mobile phone, and the authenticated device may be a headset.