--- app_amd.c	2018-10-31 12:52:41.229343351 +0000
+++ app_amd.c	2018-10-31 12:52:07.297094203 +0000
@@ -282,6 +282,8 @@
 		/* Figure out how long we waited */
 		if (res > 0) {
 			ms = 2 * maxWaitTimeForFrame - res;
+		} else {
+			ms = 2 * maxWaitTimeForFrame;
 		}
 
 		/* If we fail to read in a frame, that means they hung up */
@@ -293,7 +295,7 @@
 			break;
 		}
 
-		if (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_CNG) {
+		if (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_CNG || f->frametype == AST_FRAME_NULL) {
 			/* 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);