MC9090 DTMF/Audio questions

Background: I am trying to use the MC9090 with the Raspberry PI to build a cell phone type device. I am developing drivers for the I2S, and have some questions

DTMF Question:
I am using the AT!AVTONEPLAY command to play DTMF tones with the MC9090. The syntax is listed as: AT!AVTONEPLAY=[,]

in reality, if i pass anything but AT!AVTONEPLAY=, then i will get an error. I need to be able to play DTMF tones of different durations; any suggestions?

Audio Question:
What are the A-Law coefficients used by the MC9090? I am using 255 and 120 right now, but i’d prefer to match it exactly.

16 bit linear…what format is that? I can decode A-Law (its scratchy since my parameters are off, but understandable) but my 16 bit linear just sounds like noise. any thoughts?

Finally: is there always mono audio or can it do stereo as well?