Index: main/channel.c
===================================================================
--- main/channel.c	(revision 103805)
+++ main/channel.c	(working copy)
@@ -2166,6 +2166,15 @@
 			}
 			break;
 		case AST_FRAME_NULL:
+			/* The EMULATE_DTMF flag must be cleared here as opposed to when the duration
+			 * is reached , because we want to make sure we pass at least one
+			 * voice frame through before starting the next digit, to ensure a gap
+			 * between DTMF digits. */
+			if (ast_test_flag(chan, AST_FLAG_EMULATE_DTMF) && !chan->emulate_dtmf_duration) {
+				ast_clear_flag(chan, AST_FLAG_EMULATE_DTMF);
+				chan->emulate_dtmf_digit = 0;
+			}
+
 			if (ast_test_flag(chan, AST_FLAG_EMULATE_DTMF)) {
 				struct timeval now = ast_tvnow();
 				if (ast_tvdiff_ms(now, chan->dtmf_tv) >= chan->emulate_dtmf_duration) {