diff --git a/src/channels/chan_voicemngr.c b/src/channels/chan_voicemngr.c
index 351ed77d80e2de4f772f8a10e1ed31e027e0ccf1..208b47aa9f4978a387bde1cd6b7401a69ec137e7 100644
--- a/src/channels/chan_voicemngr.c
+++ b/src/channels/chan_voicemngr.c
@@ -2086,6 +2086,7 @@ static struct ast_channel *chan_voicemngr_new(struct chan_voicemngr_subchannel *
 	struct ast_channel *chan = NULL;
 	struct ast_format *fmt;
 	struct ast_format_cap *caps;
+	struct ast_str *buf = ast_str_alloca(256);
 
 	caps = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
 	if (!caps) {
@@ -2097,8 +2098,12 @@ static struct ast_channel *chan_voicemngr_new(struct chan_voicemngr_subchannel *
 	if (chan) {
 		ast_channel_tech_set(chan, cur_tech);
 		if (format) {
+			ast_format_cap_get_names(format, &buf);
+			ast_debug(1, "debug_tmp: create a channel with formats: %s\n", ast_str_buffer(buf));
 			ast_format_cap_append_from_cap(caps, format, AST_MEDIA_TYPE_UNKNOWN);
 		} else {
+			ast_format_cap_get_names(default_cap, &buf);
+			ast_debug(1, "debug_tmp: create a channel with default formats: %s\n", ast_str_buffer(buf));
 			ast_format_cap_append_from_cap(caps, default_cap, AST_MEDIA_TYPE_UNKNOWN);
 		}
 		ast_channel_nativeformats_set(chan, caps);