diff --git a/third_party/gsm/tst/cod2lin.c b/third_party/gsm/tst/cod2lin.c
new file mode 100644
index 0000000..07a9510
--- /dev/null
+++ b/third_party/gsm/tst/cod2lin.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
+ * Universitaet Berlin.  See the accompanying file "COPYRIGHT" for
+ * details.  THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
+ */
+
+/*$Header: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/cod2lin.c,v 1.2 1996/07/02 14:33:10 jutta Exp jutta $*/
+
+#include <stdio.h>
+#include <assert.h>
+
+#include	"gsm.h"
+#include	"proto.h"
+
+char  * pname;
+
+int	debug      = 0;
+int	verbosity  = 0;
+int	fast       = 0;
+int	wav        = 0;
+int	error      = 0;
+
+usage P0()
+{
+	fprintf(stderr, "Usage: %s [-vwF] [files...]\n", pname);
+	exit(1);
+}
+
+void process P2((f, filename), FILE * f, char * filename)
+{
+	gsm_frame	buf;
+	gsm_signal	source[160];
+
+	int		cc;
+	gsm		r;
+
+	(void)memset(source, 0x00, sizeof(source));
+
+	if (!(r = gsm_create())) {
+		perror("gsm_create");
+		error = 1;
+		return ;
+	}
+	gsm_option(r, GSM_OPT_VERBOSE, &verbosity);
+	gsm_option(r, GSM_OPT_FAST,    &fast);
+	gsm_option(r, GSM_OPT_WAV49,   &wav);
+	for (;;) {
+		cc = fread((char *)source, sizeof(*source), 76, f);
+		if (cc == 0) {
+			gsm_destroy(r);
+			return;
+		}
+		if (cc != 76) {
+			error = 1;
+			fprintf(stderr,
+				"%s: %s -- %d trailing bytes ignored\n",
+				pname, filename, cc);
+			gsm_destroy(r);
+			return;
+		}
+
+		gsm_implode(r, source, buf);
+		gsm_decode(r, buf, source);
+
+		if (write(1, source, sizeof(source)) != sizeof(source)) {
+			perror("write");
+			error = 1;
+			gsm_destroy(r);
+			return;
+		}
+	}
+}
+
+main P2((ac, av), int ac, char ** av)
+{
+	int 		opt;
+	extern char   * optarg;
+	extern int	optind;
+
+	FILE		* f;
+
+	if (!(pname = av[0])) pname = "cod2out";
+
+	while ((opt = getopt(ac, av, "vwF")) != EOF) switch (opt) {
+	case 'v': verbosity++; 	  break;
+	case 'w': wav++; 	  break;
+	case 'F': fast++;	  break;
+	default:  usage();
+	}
+
+	ac -= optind;
+	av += optind;
+
+	if (!ac) process(stdin, "*stdin*");
+	else for (; *av; av++) {
+		if (!(f = fopen(*av, "r"))) perror(*av);
+		else {
+			process(f, *av);
+			fclose(f);
+		}
+	}
+
+	exit(error);
+}