19. A user terminal of a communications network comprising: a speech synthesis engine; a basic database of speech waveforms; and an application for retrieving textual information to be converted into synthesized speech comprising: a database manager configured to: download an incremental database of speech waveforms from a database server, said incremental database being based on a context of said textual information to be synthesized determined from context information extracted from said textual information to be synthesized, and manage the composition of an enlarged speech waveforms database for said speech synthesis engine, comprising said basic and said incremental databases of speech waveforms, wherein the speech synthesis engine is configured to use at least part of the basic database and at least part of the incremental database to synthesize the speech, said speech synthesis engine starting speech synthesis of said textual information employing said basic database of speech waveforms and continuing speech synthesis of said textual information employing said enlarged database of speech waveforms.
19. A user terminal of a communications network comprising: a speech synthesis engine; a basic database of speech waveforms; and an application for retrieving textual information to be converted into synthesized speech comprising: a database manager configured to: download an incremental database of speech waveforms from a database server, said incremental database being based on a context of said textual information to be synthesized determined from context information extracted from said textual information to be synthesized, and manage the composition of an enlarged speech waveforms database for said speech synthesis engine, comprising said basic and said incremental databases of speech waveforms, wherein the speech synthesis engine is configured to use at least part of the basic database and at least part of the incremental database to synthesize the speech, said speech synthesis engine starting speech synthesis of said textual information employing said basic database of speech waveforms and continuing speech synthesis of said textual information employing said enlarged database of speech waveforms. 20. The user terminal of claim 19 , further comprising a cache memory for temporarily storing at least one downloaded incremental database.