1 files changed, 2 insertions, 0 deletions
diff --git a/soxdial b/soxdial
index e445d55..7726c8a 100755
--- a/soxdial
+++ b/soxdial
@@ -430,6 +430,8 @@ sub add_bluebox_digit {
 # --norm is needed because otherwise, the volume decreases as the number of
 # digits (tones for "synth") goes up. --norm=-3 helps avoid clipping.
 sub make_sox_subcmd {
+	return ":" unless @freqs1;
+
 	my $length = shift || $digittime;
 	my $cmd = "sox -n -b$bits $encoding -r$rate -c1 -traw - --norm=-3 ";
 	my $synth = " synth $length ";