asterisk users - Nov 2006 - Odd results from fxotune?

I recently ran fxotune against our incoming PSTN lines to try and help 
with some echo problems.

It produced the following fxotune.conf file:

2=8,253,2,244,255,10,244,3,253
3=4,0,0,0,0,0,0,0,0
4=4,0,0,0,0,0,0,0,0


I'm a bit surprised by all of the '0's for channels 3&4, esp.
given that
it's populated values for channel 2.

Is this considered 'normal' behaviour, or is something amiss?

Thanks,

j