diff --git a/bsc/MSC_ConnectionHandler.ttcn b/bsc/MSC_ConnectionHandler.ttcn
index 6afeca21f..55cdb8958 100644
--- a/bsc/MSC_ConnectionHandler.ttcn
+++ b/bsc/MSC_ConnectionHandler.ttcn
@@ -426,8 +426,9 @@ altstep as_assignment(inout AssignmentState st) runs on MSC_ConnHdlr {
 		}
 	[st.rr_ass_cmpl_seen] RSL.receive(tr_RSL_RF_CHAN_REL(st.old_chan_nr)) {
 		RSL.send(ts_RSL_RF_CHAN_REL_ACK(st.old_chan_nr));
-		/* FIXME: unregister for old channel number in RSL emulation */
-		//f_rslem_unregister(0, st.old_chan_nr);
+		/* unregister for old channel number in RSL emulation */
+		/* FIXME: Determine TRX NR by ARFCN, instead of hard-coded TRX0! */
+		f_rslem_unregister(0, st.old_chan_nr);
 		st.assignment_done := true;
 		repeat;
 		}
diff --git a/library/RSL_Emulation.ttcn b/library/RSL_Emulation.ttcn
index cbcff2c61..d20718f61 100644
--- a/library/RSL_Emulation.ttcn
+++ b/library/RSL_Emulation.ttcn
@@ -50,9 +50,10 @@ type port RSL_DCHAN_PT message {
 } with { extension "internal" };
 
 signature RSLEM_register(uint8_t trx_nr, RslChannelNr chan_nr, RSL_DchanHdlr hdlr);
+signature RSLEM_unregister(uint8_t trx_nr, RslChannelNr chan_nr, RSL_DchanHdlr hdlr);
 
 type port RSLEM_PROC_PT procedure {
-	inout RSLEM_register;
+	inout RSLEM_register, RSLEM_unregister;
 } with { extension "internal" };
 
 /***********************************************************************
@@ -379,6 +380,13 @@ function main() runs on RSL_Emulation_CT {
 			RSL_PROC.reply(RSLEM_register:{trx_nr, chan_nr, vc_conn});
 			}
 
+		[] RSL_PROC.getcall(RSLEM_unregister:{?,?,?}) -> param(trx_nr, chan_nr, vc_conn) {
+			cid := f_cid_by_chan_nr(trx_nr, chan_nr);
+			f_cid_clear(cid);
+			RSL_PROC.reply(RSLEM_unregister:{trx_nr, chan_nr, vc_conn});
+			}
+
+
 		}
 	}
 }
@@ -400,4 +408,12 @@ function f_rslem_register(uint8_t trx_nr, RslChannelNr chan_nr) runs on RSL_Dcha
 	}
 }
 
+/* client/conn_hdlr side function to use procedure port to unregister stream_id/chan_nr */
+function f_rslem_unregister(uint8_t trx_nr, RslChannelNr chan_nr) runs on RSL_DchanHdlr {
+	RSL_PROC.call(RSLEM_unregister:{trx_nr, chan_nr, self}) {
+		[] RSL_PROC.getreply(RSLEM_unregister:{?,?,?}) {};
+	}
+}
+
+
 }