22. A communication system capable of text transmission and speech session, comprising a controlling device, and a plurality of communication terminals capable of text transmission and speech session via the controlling device, wherein the controlling device is provided with the personalized text-to-speech synthesizing device according to claim 1 .
22. A communication system capable of text transmission and speech session, comprising a controlling device, and a plurality of communication terminals capable of text transmission and speech session via the controlling device, wherein the controlling device is provided with the personalized text-to-speech synthesizing device according to claim 1 . 23. The communication system according to claim 22 , wherein the controlling device further comprises: a speech feature recognition trigger device, configured to trigger the personalized text-to-speech synthesizing device to perform a personalized speech feature recognition of speech fragments of speakers in a speech session, when two or more of the plurality of communication terminals are used for the speech session via the controlling device, thereby to create and store personalized speech feature libraries associated with respective speakers in the speech session respectively; and a text-to-speech trigger synthesis device configured to enquire whether any personalized speech feature library associated with a subscriber transmitting a text message occurs in the controlling device when the controlling device receives the text messages transmitted by any of the plurality of communication terminals to another communication terminal, trigger the personalized text-to-speech synthesizing device to synthesize the text messages having been received into a speech fragment when the enquiry result is affirmative, and transfer the speech fragment to the another communication terminal.