As turned out, problem with 406 error appeared when settings of encryption was incorrect.
SILK_WB now work fine on 16000, thanks for info about bitrate.
Both codecs, SILK-8000 and SILK-16000, now work good with CSipSimple softphone (version 0.03-01). I think, this means that Asterisk server configured right.
But still present problem with 488 error at attempt to answer call. It appear only if i enable SILK_NB codec.
If i disable NB and enable WB, then problem disappear and calls accepted normally.
Outgoing calls are succesfull at all codecs.
Looks like this trouble is specific to Bria and SILK_NB(maybe, only in android edition).
I found info about similar bug
in early versions of CSipSimple:
Problem - is disparity ids of codecs in "rtpmap" parameters in Asterisk and Bria SDP messages.
CSipSimple developer resolved this trouble when he changed a default bitrate for codec in his application.
I will attempt to talk with Bria support for made similar fix in their product.