diff --git a/library/AMR_Types.ttcn b/library/AMR_Types.ttcn
new file mode 100644
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--- /dev/null
+++ b/library/AMR_Types.ttcn
@@ -0,0 +1,38 @@
+/*
+ * (C) 2019-2022 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All rights reserved.
+ *
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ */
+
+module AMR_Types {
+
+import from General_Types all;
+
+/* AMR voice frame type identifiers
+ * See also 3GPP TS 26.101, Table 1a: Interpretation of Frame Type, Mode
+ * Indication and Mode Request fields */
+type enumerated AMRFT {
+  AMR_FT_0,	/* 4.75 */
+  AMR_FT_1,	/* 5.15 */
+  AMR_FT_2,	/* 5.90 */
+  AMR_FT_3,	/* 6.70 */
+  AMR_FT_4,	/* 7.40 */
+  AMR_FT_5,	/* 7.95 */
+  AMR_FT_6,	/* 10.2 */
+  AMR_FT_7,	/* 12.2 */
+  AMR_FT_SID	/* SID */
+};
+
+/* AMR voice frame length (in bytes, rounded),
+ * See also RFC 3267, chapter 3.6 */
+const integer c_AMRFT_len[9] := {12, 13, 15, 17, 19, 20, 26, 31, 5};
+
+function f_amrft_payload_len(INT4b amr_ft) return integer {
+        return c_AMRFT_len[amr_ft];
+}
+
+} with { encode "RAW"}