diff -dur asterisk-13.7.2.orig/main/codec_builtin.c asterisk-13.7.2/main/codec_builtin.c
--- asterisk-13.7.2.orig/main/codec_builtin.c	2016-02-05 21:32:40.000000000 +0100
+++ asterisk-13.7.2/main/codec_builtin.c	2016-03-09 11:55:44.000000000 +0100
@@ -38,6 +38,8 @@
 #include "asterisk/format_cache.h"
 #include "asterisk/frame.h"
 
+#include <opus/opus.h>
+
 enum frame_type {
 	TYPE_HIGH,     /* 0x0 */
 	TYPE_LOW,      /* 0x1 */
@@ -698,6 +700,11 @@
 	.get_length = g719_length,
 };
 
+static int opus_samples(struct ast_frame *frame)
+{
+	return opus_packet_get_nb_samples(frame->data.ptr, frame->datalen, 48000);
+}
+
 static struct ast_codec opus = {
 	.name = "opus",
 	.description = "Opus Codec",
@@ -707,6 +714,7 @@
 	.maximum_ms = 60,
 	.default_ms = 20,
 	.minimum_bytes = 10,
+	.samples_count = opus_samples,
 };
 
 static struct ast_codec jpeg = {
diff -dur asterisk-13.7.2.orig/main/Makefile asterisk-13.7.2/main/Makefile
--- asterisk-13.7.2.orig/main/Makefile	2016-03-09 11:53:45.000000000 +0100
+++ asterisk-13.7.2/main/Makefile	2016-03-09 11:55:44.000000000 +0100
@@ -40,6 +40,7 @@
 AST_LIBS+=$(URIPARSER_LIB)
 AST_LIBS+=$(UUID_LIB)
 AST_LIBS+=$(CRYPT_LIB)
+AST_LIBS+=$(OPUS_LIB)
 AST_LIBS+=$(AST_CLANG_BLOCKS_LIBS)
 
 ifneq ($(findstring $(OSARCH), linux-gnu linux-gnux32 uclinux linux-uclibc kfreebsd-gnu),)
@@ -160,6 +161,7 @@
 bucket.o: _ASTCFLAGS+=$(URIPARSER_INCLUDE)
 crypt.o: _ASTCFLAGS+=$(CRYPT_INCLUDE)
 uuid.o: _ASTCFLAGS+=$(UUID_INCLUDE)
+codec_builtin.o: _ASTCFLAGS+=$(OPUS_INCLUDE)
 
 ifneq ($(findstring ENABLE_UPLOADS,$(MENUSELECT_CFLAGS)),)
 http.o: _ASTCFLAGS+=$(GMIME_INCLUDE)