diff --git a/apps/app_amd.c b/apps/app_amd.c
index e10f2cc011..3f805bb9ab 100644
--- a/apps/app_amd.c
+++ b/apps/app_amd.c
@@ -277,6 +277,12 @@ static void isAnsweringMachine(struct ast_channel *chan, const char *data)
 
 	/* Now we go into a loop waiting for frames from the channel */
 	while ((res = ast_waitfor(chan, 2 * maxWaitTimeForFrame)) > -1) {
+		int ms = 0;
+
+		/* Figure out how long we waited */
+		if (res > 0) {
+			ms = 2 * maxWaitTimeForFrame - res;
+		}
 
 		/* If we fail to read in a frame, that means they hung up */
 		if (!(f = ast_read(chan))) {
@@ -287,15 +293,22 @@ static void isAnsweringMachine(struct ast_channel *chan, const char *data)
 			break;
 		}
 
-		if (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_NULL || f->frametype == AST_FRAME_CNG) {
-			/* If the total time exceeds the analysis time then give up as we are not too sure */
+		if (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_CNG) {
+			/* Figure out how long the frame is in milliseconds */
 			if (f->frametype == AST_FRAME_VOICE) {
 				framelength = (ast_codec_samples_count(f) / DEFAULT_SAMPLES_PER_MS);
 			} else {
-				framelength = 2 * maxWaitTimeForFrame;
+				framelength = ms;
 			}
 
 			iTotalTime += framelength;
+
+			ast_debug(1, "AMD: Channel [%s] frametype [%s] iTotalTime [%d] framelength [%d] totalAnalysisTime [%d]\n",
+					  ast_channel_name(chan),
+					  f->frametype == AST_FRAME_VOICE ? "AST_FRAME_VOICE" : "AST_FRAME_CNG",
+					  iTotalTime, framelength, totalAnalysisTime);
+
+			/* If the total time exceeds the analysis time then give up as we are not too sure */
 			if (iTotalTime >= totalAnalysisTime) {
 				ast_verb(3, "AMD: Channel [%s]. Too long...\n", ast_channel_name(chan));
 				ast_frfree(f);
@@ -306,7 +319,7 @@ static void isAnsweringMachine(struct ast_channel *chan, const char *data)
 
 			/* Feed the frame of audio into the silence detector and see if we get a result */
 			if (f->frametype != AST_FRAME_VOICE)
-				dspsilence += 2 * maxWaitTimeForFrame;
+				dspsilence += framelength;
 			else {
 				dspsilence = 0;
 				ast_dsp_silence(silenceDetector, f, &dspsilence);