Techniques for 
discontinuous transmission (DTX) and fast in-band signaling of configuration changes and protocol messages in speech communications systems provide 
cost efficiency in terms of 
radio transmission capacity, in terms of fixed line transmission, and in terms of implementation effort. An exemplary method for performing 
discontinuous transmission (DTX) in a 
communications system in which 
source data is interleaved for transmission from a first component in the 
system to a second component in the 
system includes the steps of detecting periods of 
source data inactivity, and transmitting 
silence descriptor (SID) frames from the first to the second component during the periods of 
source data inactivity, certain of the transmitted SID frames being interleaved using a different 
interleaving algorithm as compared to that used for source data. For example, the source data can be block diagonally interleaved, and certain of the SID frames can be block interleaved. An exemplary method for effecting configuration changes in a 
communications system includes the step of transmitting an escape frame in place of a speech data frame, the escape frame including a gross bit pattern to distinguish the escape frame from speech data frames and conveying a configuration change indication. The escape frame can further include a 
data field to indicate a particular configuration change to be made. For example, where the 
communications system is an AMR 
system, an escape frame can be used to change an active codec mode set. Alternatively, an escape frame can be used to change a phase of codec information.