Index: include/asterisk/pbx.h
===================================================================
--- a/include/asterisk/pbx.h	(revision 112598)
+++ b/include/asterisk/pbx.h	(working copy)
@@ -42,6 +42,7 @@

 /*! \brief Special return values from applications to the PBX { */
 #define AST_PBX_ERROR	        1	/*!< Jump to the 'e' exten */
+#define AST_PBX_INCOMPLETE	12	/*!< Return to PBX matching, allowing more digits for the extension */
 /*! } */
 
 #define PRIORITY_HINT	-1	/*!< Special Priority for a hint */
Index: main/pbx.c
===================================================================
--- a/main/pbx.c	(revision 112598)
+++ b/main/pbx.c	(working copy)
@@ -302,6 +302,7 @@
 static int pbx_builtin_background(struct ast_channel *, void *);
 static int pbx_builtin_wait(struct ast_channel *, void *);
 static int pbx_builtin_waitexten(struct ast_channel *, void *);
+static int pbx_builtin_incomplete(struct ast_channel *, void *);
 static int pbx_builtin_resetcdr(struct ast_channel *, void *);
 static int pbx_builtin_setamaflags(struct ast_channel *, void *);
 static int pbx_builtin_ringing(struct ast_channel *, void *);
@@ -579,6 +580,16 @@
 	"value.\n"
 	},
 
+	{ "Incomplete", pbx_builtin_incomplete,
+	"returns AST_PBX_INCOMPLETE value",
+	"  Incomplete([n]): Signals the PBX routines that the previous matched extension\n"
+	"is incomplete and that further input should be allowed before matching can\n"
+	"be considered to be complete.  Can be used within a pattern match when\n"
+	"certain criteria warrants a longer match.\n"
+	"  If the 'n' option is specified, then Incomplete will not attempt to answer\n"
+	"the channel first.  Note that most channel types need to be in Answer state\n"
+	"in order to receive DTMF.\n"
+	},
 	{ "NoOp", pbx_builtin_noop,
 	"Do Nothing (No Operation)",
 	"  NoOp(): This application does nothing. However, it is useful for debugging\n"
@@ -3539,6 +3551,8 @@
 		char dst_exten[256];	/* buffer to accumulate digits */
 		int pos = 0;		/* XXX should check bounds */
 		int digit = 0;
+		int invalid = 0;
+		int timeout = 0;
 
 		/* loop on priorities in this context/exten */
 		while ( !(res = ast_spawn_extension(c, c->context, c->exten, c->priority, c->cid.cid_num, &found,1))) {
@@ -3574,6 +3588,18 @@
 				pos = 0;
 				dst_exten[pos++] = digit = res;
 				dst_exten[pos] = '\0';
+			} else if (res == AST_PBX_INCOMPLETE) {
+				ast_debug(1, "Spawn extension (%s,%s,%d) exited INCOMPLETE on '%s'\n", c->context, c->exten, c->priority, c->name);
+				ast_verb(2, "Spawn extension (%s, %s, %d) exited INCOMPLETE on '%s'\n", c->context, c->exten, c->priority, c->name);
+
+				/* Don't cycle on incomplete - this will happen if the only extension that matches is our "incomplete" extension */
+				if (!ast_matchmore_extension(c, c->context, c->exten, c->priority, c->cid.cid_num)) {
+					invalid = 1;
+				} else {
+					ast_copy_string(dst_exten, c->exten, sizeof(dst_exten));
+					digit = 1;
+					pos = strlen(dst_exten);
+				}
 			} else {
 				ast_debug(1, "Spawn extension (%s,%s,%d) exited non-zero on '%s'\n", c->context, c->exten, c->priority, c->name);
 				ast_verb(2, "Spawn extension (%s, %s, %d) exited non-zero on '%s'\n", c->context, c->exten, c->priority, c->name);
@@ -3610,7 +3636,7 @@
 		 * hangup.  We have options, here.  We can either catch the failure
 		 * and continue, or we can drop out entirely. */
 
-		if (!ast_exists_extension(c, c->context, c->exten, 1, c->cid.cid_num)) {
+		if (invalid || !ast_exists_extension(c, c->context, c->exten, 1, c->cid.cid_num)) {
 			/*!\note
 			 * If there is no match at priority 1, it is not a valid extension anymore.
 			 * Try to continue at "i" (for invalid) or "e" (for exception) or exit if
@@ -3654,11 +3680,13 @@
 
 			if (collect_digits(c, waittime, dst_exten, sizeof(dst_exten), pos))
 				break;
-			if (ast_exists_extension(c, c->context, dst_exten, 1, c->cid.cid_num)) /* Prepare the next cycle */
+			if (res == AST_PBX_INCOMPLETE && ast_strlen_zero(&dst_exten[pos]))
+				timeout = 1;
+			if (!timeout && ast_exists_extension(c, c->context, dst_exten, 1, c->cid.cid_num)) /* Prepare the next cycle */
 				set_ext_pri(c, dst_exten, 1);
 			else {
 				/* No such extension */
-				if (!ast_strlen_zero(dst_exten)) {
+				if (!timeout && !ast_strlen_zero(dst_exten)) {
 					/* An invalid extension */
 					if (ast_exists_extension(c, c->context, "i", 1, c->cid.cid_num)) {
 						ast_verb(3, "Invalid extension '%s' in context '%s' on %s\n", dst_exten, c->context, c->name);
@@ -7315,6 +7343,26 @@
 	return AST_PBX_KEEPALIVE;
 }
 
+static int pbx_builtin_incomplete(struct ast_channel *chan, void *data)
+{
+	char *options = data;
+	int answer = 1;
+
+	/* Some channels can receive DTMF in unanswered state; some cannot */
+	if (!ast_strlen_zero(options) && strchr(options, 'n')) {
+		answer = 0;
+	}
+
+	/* If the channel is hungup, stop waiting */
+	if (ast_check_hangup(chan)) {
+		return -1;
+	} else if (chan->_state != AST_STATE_UP && answer) {
+		__ast_answer(chan, 0, 1);
+	}
+
+	return AST_PBX_INCOMPLETE;
+}
+
 AST_APP_OPTIONS(resetcdr_opts, {
 	AST_APP_OPTION('w', AST_CDR_FLAG_POSTED),
 	AST_APP_OPTION('a', AST_CDR_FLAG_LOCKED),