diff --git a/openbsc/src/abis_rsl.c b/openbsc/src/abis_rsl.c
index 047c768..5b708aa 100644
--- a/openbsc/src/abis_rsl.c
+++ b/openbsc/src/abis_rsl.c
@@ -1505,6 +1505,12 @@
 
 static u_int8_t ipa_rtp_pt_for_lchan(struct gsm_lchan *lchan)
 {
+	struct gsm_network *net = lchan->ts->trx->bts->network;
+
+	/* allow to hardcode the rtp payload */
+	if (net->hardcoded_rtp_payload != 0)
+		return net->hardcoded_rtp_payload;
+
 	switch (lchan->tch_mode) {
 	case GSM48_CMODE_SPEECH_V1:
 		switch (lchan->type) {