diff --git a/openbsc/include/openbsc/gsm_data_shared.h b/openbsc/include/openbsc/gsm_data_shared.h
index f4da7a7..b4ff0a4 100644
--- a/openbsc/include/openbsc/gsm_data_shared.h
+++ b/openbsc/include/openbsc/gsm_data_shared.h
@@ -825,8 +825,11 @@
 /* reset the state of all MO in the BTS */
 void gsm_bts_mo_reset(struct gsm_bts *bts);
 
-uint8_t gsm_ts2chan_nr(const struct gsm_bts_trx_ts *ts, uint8_t lchan_nr);
+uint8_t gsm_pchan2chan_nr(enum gsm_phys_chan_config pchan,
+			  uint8_t ts_nr, uint8_t lchan_nr);
 uint8_t gsm_lchan2chan_nr(const struct gsm_lchan *lchan);
+uint8_t gsm_lchan_as_pchan2chan_nr(const struct gsm_lchan *lchan,
+				   enum gsm_phys_chan_config as_pchan);
 
 /* return the gsm_lchan for the CBCH (if it exists at all) */
 struct gsm_lchan *gsm_bts_get_cbch(struct gsm_bts *bts);
diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index 664b1a6..868375f 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -2048,7 +2048,7 @@
 	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
 	init_dchan_hdr(dh, msg_type);
 	dh->c.msg_discr = ABIS_RSL_MDISC_DED_CHAN;
-	dh->chan_nr = gsm_ts2chan_nr(ts, 0);
+	dh->chan_nr = gsm_pchan2chan_nr(GSM_PCHAN_PDCH, ts->nr, 0);
 
 	DEBUGP(DRSL, "%s IPAC PDCH %sACT\n", gsm_ts_name(ts),
 		act ? "" : "DE");
diff --git a/openbsc/src/libcommon/gsm_data_shared.c b/openbsc/src/libcommon/gsm_data_shared.c
index 14c33d7..84c57c3 100644
--- a/openbsc/src/libcommon/gsm_data_shared.c
+++ b/openbsc/src/libcommon/gsm_data_shared.c
@@ -552,11 +552,12 @@
 }
 
 /* See Table 10.5.25 of GSM04.08 */
-uint8_t gsm_ts2chan_nr(const struct gsm_bts_trx_ts *ts, uint8_t lchan_nr)
+uint8_t gsm_pchan2chan_nr(enum gsm_phys_chan_config pchan,
+			  uint8_t ts_nr, uint8_t lchan_nr)
 {
 	uint8_t cbits, chan_nr;
 
-	switch (ts->pchan) {
+	switch (pchan) {
 	case GSM_PCHAN_TCH_F:
 	case GSM_PCHAN_PDCH:
 	case GSM_PCHAN_TCH_F_PDCH:
@@ -596,14 +597,20 @@
 		break;
 	}
 
-	chan_nr = (cbits << 3) | (ts->nr & 0x7);
+	chan_nr = (cbits << 3) | (ts_nr & 0x7);
 
 	return chan_nr;
 }
 
 uint8_t gsm_lchan2chan_nr(const struct gsm_lchan *lchan)
 {
-	return gsm_ts2chan_nr(lchan->ts, lchan->nr);
+	return gsm_pchan2chan_nr(lchan->ts->pchan, lchan->ts->nr, lchan->nr);
+}
+
+uint8_t gsm_lchan_as_pchan2chan_nr(const struct gsm_lchan *lchan,
+				   enum gsm_phys_chan_config as_pchan)
+{
+	return gsm_pchan2chan_nr(as_pchan, lchan->ts->nr, lchan->nr);
 }
 
 /* return the gsm_lchan for the CBCH (if it exists at all) */