26 series - Voice and audio codecs

Description

The voice & audio specifications that are listed here cover the following issues:

• Echo control at the interface to the public switched telephone network.
• The acoustic characteristics of 3G phones.
• The codecs supported during transcoder-free operation, in which the compressed speech frames travel all the way from one mobile to the other, without any transcoders in the communication path.
• Text telephones for the hard-of-hearing.
• Distributed speech recognition, in which the speech is parameterised before transmission, so as to avoid degradation of the signal over the radio interface.

The codecs themselves (AMR, AMR-WB and enhanced aacPlus) are covered on the pages indicated at the top.

Abbreviations