It is possible for no audio to pass between the current digit and next digit so expand logic that clears emulation to AST_FRAME_NULL.

(closes issue #11911)
Reported by: edgreenberg
Patches:
      v1-11911.patch uploaded by dimas (license 88)
Tested by: tbsky


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@105560 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/channel.c

@@ -2166,9 +2166,16 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 			}
 			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)) {
 				struct timeval now = ast_tvnow();
-				if (ast_tvdiff_ms(now, chan->dtmf_tv) >= chan->emulate_dtmf_duration) {
+				if (!chan->emulate_dtmf_duration) {
+					ast_clear_flag(chan, AST_FLAG_EMULATE_DTMF);
+					chan->emulate_dtmf_digit = 0;
+				} else if (ast_tvdiff_ms(now, chan->dtmf_tv) >= chan->emulate_dtmf_duration) {
 					chan->emulate_dtmf_duration = 0;
 					ast_frfree(f);
 					f = &chan->dtmff;