diff --git a/bts/BTS_Tests_LAPDm.ttcn b/bts/BTS_Tests_LAPDm.ttcn
index 6d252e0..edd974b 100644
--- a/bts/BTS_Tests_LAPDm.ttcn
+++ b/bts/BTS_Tests_LAPDm.ttcn
@@ -43,7 +43,8 @@
 
 /* master function switching to a dedicated radio channel */
 function f_switch_dcch() runs on ConnHdlr {
-	var GsmBandArfcn arfcn := valueof(ts_GsmBandArfcn(mp_trx_pars[0].arfcn));
+	var TrxParsItem trx_pars := mp_trx_pars[g_pars.trx_nr];
+	var GsmBandArfcn arfcn := valueof(ts_GsmBandArfcn(trx_pars.arfcn));
 	var BCCH_tune_req tune_req := { arfcn := arfcn, combined_ccch := true };
 	var DCCH_switch_req sw_req;
 
@@ -55,7 +56,7 @@
 		sw_req.ma := g_pars.fhp.ma;
 	} else {
 		sw_req.chan_desc := valueof(ts_ChanDescH0(g_pars.chan_nr,
-							  mp_trx_pars[0].arfcn,
+							  trx_pars.arfcn,
 							  g_pars.tsc));
 		sw_req.ma := omit;
 	}