"Sagem GSM phone let's you hear the other party's audio before you pick up" - Demonstrated this last time about 6 years ago calling my phone from different networks: fixed, and two other GSM. My conclusion was that it's an implementation bug easy to trip on or a provision in standard that it's easy to misread.

Now - if the audio channel is _right there_ for you to read, what chances are for this to be only a Sagem firmware bug?