| 摘要 |
<p>The invention enables the introduction of a codec (108, 128) according to a new speech encoding method into a speech transmitting tansceiver (100) of a digital telecommunications system, so that it is possible to use a 'new' codec (108, 128) and an 'old' codec (106, 126) in parallel in the system. A codec is selected by implementing a handshaking procedure according to the invention between the transceivers (100, 100'). The invention is based on handshaking in which a speech encoding method implemented in all the transceivers (100, 100') and previously used in the telecommunications system concerned is used first at the beginning of each connection. At the beginning of a phone call and after handover, the method checks whether both parties (100, 100') can also use the new speech encoding. The handshaking messages have been selected so that their effect on the quality of speech is minimal, and yet so that the probability of identifying the messages is maximal.</p> |
