hi sylvain, what do you mean with "much"? i filter the channel with the channel request number (includes random number) in the IMM.ASS message. maybe in the future we can filter the time slot where it was sent (RACH confirm) and compare it also. but this requires RACH confirm with GSM time where it was sent. andreas @harald: is there any time stamp in the RACH confirm? what format would it be? .... from the IMM.ASS parsing: /* 3.3.1.1.2: ignore assignment while idle */ if (rr->state != GSM48_RR_ST_CONN_PEND || !rr->wait_assign) { LOGP(DRR, LOGL_INFO, "Not for us, no request.\n"); return 0; } /* request ref */ if (gsm48_match_ra(ms, &ia->req_ref)) { /* channel description */ memcpy(&rr->cd_now, &cd, sizeof(rr->cd_now)); /* timing advance */ rr->cd_now.ta = ia->timing_advance; /* mobile allocation */ memcpy(&rr->cd_now.mob_alloc_lv, &ia->mob_alloc_len, ia->mob_alloc_len + 1); rr->wait_assign = 0; return gsm48_rr_dl_est(ms); } LOGP(DRR, LOGL_INFO, "Request, but not for us.\n");