This attribute specifies an alternateIdlePattern in the channel
received from the E1 interface, after the end of a 64kbit/s call.
The value of this attribute should be different than the value of the
idlePattern attribute only if the ISC is programmed for Even/Odd
Bit Inversion (EBI/OBI). This is only the case when the ISC is
performing A to Mu or Mu to A Law conversion.
When the end of the alternateIdlePattern is detected it indicates the
start of a new speech call.