Dahdi chan_mobile no outbound audio

am new to asterisk.

ubuntu server 3.0.0-14-generic-pae
atcom ax1600p
csr bluetooth usb
nokia 2730 classic

in extensions.conf
exten => 5555,1,Dial(Mobile/2730c/xxxxxxxxx,mt)

moh is a sln music file, moh is working.

finally got nearly everything working except for:
on dahdi -> cellphone calls, cellphone “callee” cannot hear dahdi caller

keep getting this scrolling warning
[Jan 13 11:55:33] WARNING[7309]: frame.c:214 __ast_smoother_feed: Smoother was working on ulaw format frames, now trying to feed slin?

if the moh option is taken out
exten => 5555,1,Dial(Mobile/2730c/xxxxxxxxx,t)
everything is ok

is this a bug?