diff -Naru asterisk-14.5.0_orig/channels/chan_sip.c asterisk-14.5.0/channels/chan_sip.c
--- asterisk-14.5.0_orig/channels/chan_sip.c	2017-05-31 02:50:46.000000000 +0900
+++ asterisk-14.5.0/channels/chan_sip.c	2017-06-16 17:20:51.662231445 +0900
@@ -15546,8 +15546,9 @@
 {
 	const char *channame = astman_get_header(m, "Channel");
 	struct ast_variable *vars = astman_get_variables_order(m, ORDER_NATURAL);
-	struct sip_pvt *p;
+	struct sip_pvt *p = NULL;
 	struct ast_variable *header, *var;
+	char indialog = 0;
 
 	if (ast_strlen_zero(channame)) {
 		astman_send_error(s, m, "SIPNotify requires a channel name");
@@ -15558,25 +15559,61 @@
 		channame += 4;
 	}
 
-	if (!(p = sip_alloc(NULL, NULL, 0, SIP_NOTIFY, NULL, 0))) {
-		astman_send_error(s, m, "Unable to build sip pvt data for notify (memory/socket error)");
-		return 0;
-	}
+        // check if Call-ID variable is set
+        for (var = vars; var; var = var->next) {
+          if (!strcasecmp(var->name, "Call-ID")) {
+            struct sip_pvt tmp_dialog = {
+              .callid = var->value,
+            };
+
+            p = ao2_find(dialogs, &tmp_dialog, OBJ_POINTER);
+            if (!p) {
+              astman_send_error(s, m, "Call-ID not found");
+              return 0;
+            }
+            indialog = 1;
+          }
+        }
+
+        if (!indialog) {
+		if (!(p = sip_alloc(NULL, NULL, 0, SIP_NOTIFY, NULL, 0))) {
+			astman_send_error(s, m, "Unable to build sip pvt data for notify (memory/socket error)");
+			return 0;
+		}
 
-	if (create_addr(p, channame, NULL, 0)) {
-		/* Maybe they're not registered, etc. */
-		dialog_unlink_all(p);
-		dialog_unref(p, "unref dialog inside for loop" );
-		/* sip_destroy(p); */
-		astman_send_error(s, m, "Could not create address");
-		return 0;
-	}
+		if (create_addr(p, channame, NULL, 0)) {
+			/* Maybe they're not registered, etc. */
+			dialog_unlink_all(p);
+			dialog_unref(p, "unref dialog inside for loop" );
+			/* sip_destroy(p); */
+			astman_send_error(s, m, "Could not create address");
+			return 0;
+		}
 
-	/* Notify is outgoing call */
-	ast_set_flag(&p->flags[0], SIP_OUTGOING);
-	sip_notify_alloc(p);
+		/* Notify is outgoing call */
+		ast_set_flag(&p->flags[0], SIP_OUTGOING);
+		sip_notify_alloc(p);
+
+		p->notify->headers = header = ast_variable_new("Subscription-State", "terminated", "");
+        } else {
+          if (!(p->notify)) {
+	    sip_notify_alloc(p);
+          } else {
+            ast_variables_destroy(p->notify->headers);
+          }
+
+	  p->notify->headers = header = ast_variable_new("Subscription-State", "terminated", "");
+	}
 
-	p->notify->headers = header = ast_variable_new("Subscription-State", "terminated", "");
+        /* if (pref) {
+          ast_string_field_set(p, callid, pref->callid);
+          ast_string_field_set(p, fromuser, pref->fromuser);
+          ast_string_field_set(p, fromname, pref->fromname);
+          ast_string_field_set(p, tag, pref->tag);
+          ast_string_field_set(p, theirtag, pref->theirtag);
+          p->ocseq = pref->ocseq;
+          (pref->ocseq)++;
+        } */
 
 	for (var = vars; var; var = var->next) {
 		if (!strcasecmp(var->name, "Content")) {
@@ -15585,21 +15622,27 @@
 			ast_str_append(&p->notify->content, 0, "%s", var->value);
 		} else if (!strcasecmp(var->name, "Content-Length")) {
 			ast_log(LOG_WARNING, "it is not necessary to specify Content-Length, ignoring\n");
+		} else if (!strcasecmp(var->name, "Call-ID")) {
+                  // do nothing here
 		} else {
 			header->next = ast_variable_new(var->name, var->value, "");
 			header = header->next;
 		}
 	}
 
+        if (!indialog) {
 	/* Now that we have the peer's address, set our ip and change callid */
 	ast_sip_ouraddrfor(&p->sa, &p->ourip, p);
 	build_via(p);
 
-	change_callid_pvt(p, NULL);
+        change_callid_pvt(p, NULL);
 
 	sip_scheddestroy(p, SIP_TRANS_TIMEOUT);
 	transmit_invite(p, SIP_NOTIFY, 0, 2, NULL);
 	dialog_unref(p, "bump down the count of p since we're done with it.");
+        } else {
+          transmit_invite(p, SIP_NOTIFY, 0, 1, NULL);
+        }
 
 	astman_send_ack(s, m, "Notify Sent");
 	ast_variables_destroy(vars);