diff --git a/library/AMR_Types.ttcn b/library/AMR_Types.ttcn
index 3ef2fbc..b4f044d 100644
--- a/library/AMR_Types.ttcn
+++ b/library/AMR_Types.ttcn
@@ -11,6 +11,7 @@
 module AMR_Types {
 
 import from General_Types all;
+import from Osmocom_Types all;
 
 /* AMR voice frame type identifiers
  * See also 3GPP TS 26.101, Table 1a: Interpretation of Frame Type, Mode
@@ -35,4 +36,29 @@
         return c_AMRFT_len[amr_ft];
 }
 
+type record RTP_AMR_Hdr {
+	uint4_t cmr,
+	BIT4 padding1,
+	BIT1 f,
+	uint4_t ft,
+	BIT1 q,
+	BIT2 padding2
+} with { variant "FIELDORDER(msb)" };
+
+template (value) RTP_AMR_Hdr ts_RTP_AMR_Hdr(template (value) uint4_t cmr,
+					    template (value) uint4_t ft,
+					    template (value) BIT1 q := '1'B,
+					    template (value) BIT1 f := '0'B) := {
+	cmr := cmr,
+	padding1 := '0000'B,
+	f := f,
+	ft := ft,
+	q := q,
+	padding2 := '00'B
+}
+external function enc_RTP_AMR_Hdr(in RTP_AMR_Hdr amr_hdr) return octetstring
+        with { extension "prototype(convert) encode(RAW)" };
+external function dec_RTP_AMR_Hdr(in octetstring stream) return RTP_AMR_Hdr
+        with { extension "prototype(convert) decode(RAW)" };
+
 } with { encode "RAW"}