diff --git a/include/osmocore/rsl.h b/include/osmocore/rsl.h
index 0da0520..4c5f75b 100644
--- a/include/osmocore/rsl.h
+++ b/include/osmocore/rsl.h
@@ -13,6 +13,8 @@
 
 /* encode channel number as per Section 9.3.1 */
 uint8_t rsl_enc_chan_nr(uint8_t type, uint8_t subch, uint8_t timeslot);
+/* decode channel number as per Section 9.3.1 */
+int rsl_dec_chan_nr(uint8_t chan_nr, uint8_t *type, uint8_t *subch, uint8_t *timeslot);
 
 const struct value_string rsl_rlm_cause_strs[];