AMR support and B_PLAY_UL

Hi, I tried to add simple AMR support in osmocombb project. I tested it with C123 (DSP API v 36). I set AMR config from assigment command, set AMR detection thresholds, make sync, etc. It looks like downlink works fine, but I have problem with uplink: it send data directly from microphone and ignore data in dsp_api.ndb->a_du_1 even if I set dsp_api.ndb->d_tch_mode|=B_PLAY_UL. Also, I can see uplink data on dsp_api.ndb->a_du_0 like B_PLAY_UL is fully ignored. Did anyone have that issue before? I know that AMR codec is more complex that TCH, but did someone know a way to send custom data from host using AMR codec? Best regards, Anton