You don't have 32 DSPs but 32 DSP resources on 2 DSPs.
Conferencing requires a dedicated DSP and cannot be shared
with xcode or voice.
Pl. use sh voice dsp groiup all to check dsp resource allocation
for both DSPs on the system.
Pretty sure that u don't have enough DSPs for your config.
FYI, pl. use dsp calc to figure out dsp resources needed depending
on tdm termination/codec/xcoders/conf /mtp:
http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl