Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 37122)
+++ channels/chan_sip.c	(working copy)
@@ -4121,6 +4121,7 @@
 	char *tag = "";	/* note, tag is never NULL */
 	char totag[128];
 	char fromtag[128];
+	int found;
 	const char *callid = get_header(req, "Call-ID");
 	const char *from = get_header(req, "From");
 	const char *to = get_header(req, "To");
@@ -4149,7 +4150,7 @@
 	ast_mutex_lock(&iflock);
 	for (p = iflist; p; p = p->next) {
 		/* In pedantic, we do not want packets with bad syntax to be connected to a PVT */
-		int found = FALSE;
+		found = FALSE;
 		if (req->method == SIP_REGISTER)
 			found = (!strcmp(p->callid, callid));
 		else 
@@ -4159,21 +4160,33 @@
 		if (option_debug > 4)
 			ast_log(LOG_DEBUG, "= %s Their Call ID: %s Their Tag %s Our tag: %s\n", found ? "Found" : "No match", p->callid, p->theirtag, p->tag);
 
-		/* If we get a new request within an existing to-tag - check the to tag as well */
-		if (pedanticsipchecking && found  && req->method != SIP_RESPONSE) {	/* SIP Request */
-			if (p->tag[0] == '\0' && totag[0]) {
-				/* We have no to tag, but they have. Wrong dialog */
+                /* If pedantic Check to and from tags to make sure we have the right dialog */
+		if (pedanticsipchecking && found) {
+			if (!fromtag[0]) {					
+				ast_log(LOG_WARNING, "Pedantic sip checking and no from tag for callid: %s method %s\n", callid, sip_methods[req->method].text);
+				break;
+			}
+			if (req->method == SIP_INVITE && totag[0] == '\0') {    /* no to tag it's not a reinvite, create new chan */
 				found = FALSE;
-			} else if (totag[0]) {			/* Both have tags, compare them */
-				if (strcmp(totag, p->tag)) {
-					found = FALSE;		/* This is not our packet */
+				break;
+			} else if (req->method == SIP_CANCEL && totag[0] == '\0') {    /* cancel has no to tag, check this isn't the originating chan */
+				if (!strcmp(fromtag, p->tag)) {
+					found = FALSE;
+					continue;
 				}
 			}
-			if (!found && option_debug > 4)
-				ast_log(LOG_DEBUG, "= Being pedantic: This is not our match on request: Call ID: %s Ourtag <null> Totag %s Method %s\n", p->callid, totag, sip_methods[req->method].text);
+			if (req->method != SIP_RESPONSE) {			/* request is for this chan if to tag matches */
+				if (totag[0]) {
+					if (strcmp(totag, p->tag))
+						found = FALSE;
+				}
+			} else {						/* from tag matches us it's a response to request from this chan */
+				if (strcmp(fromtag, p->tag)){
+					found = FALSE;
+				} 
+			}
 		}
 
-
 		if (found) {
 			/* Found the call */
 			ast_mutex_lock(&p->lock);