diff --git a/doc/siproxd.conf.example b/doc/siproxd.conf.example
index 9e65344..88b411e 100644
--- a/doc/siproxd.conf.example
+++ b/doc/siproxd.conf.example
@@ -530,15 +530,15 @@ plugin_fix_fbox_anoncall_networks = 192.168.0.0/16,10.0.0.0/8,172.16.0.0/20
 #
 # This plugin maintains count of failed REGISTER attempts of
 # individual local UACs (clients) and does block outgoing requests
-# from such a UAC once a limit /hitcount) has been reached. The 
+# from such a UAC once a limit (hitcount) has been reached. The 
 # duration of the block is configurable. It is required that a blocked
 # UAC does *not* send any packets that are going to be blocked
-# during the duration to recover (the UAC must remain silent during 
-# this period)
+# during the recovery duration the UAC must remain silent during 
+# this period).
 #
 # ...dbpath:          path where the database is located
 # ...mode:            0: no block, 1: IP based, 2: IP and SIP-user based
-# ...simulate:        0: block UACs once the failure count limit has been reached
+# ...simulate:        0: block UACs once the failure limit is reached
 #                     1: simulate, only log but don't block
 # ...duration:        block duration in seconds, 0: forever
 # ...hitcount:        required failed REGISTER attempts until blocked.
diff --git a/src/plugin_blacklist.c b/src/plugin_blacklist.c
index dc4d654..b977a0b 100644
--- a/src/plugin_blacklist.c
+++ b/src/plugin_blacklist.c
@@ -254,6 +254,7 @@ static int blacklist_check(sip_ticket_t *ticket) {
    osip_uri_t *from_url = NULL;
    char *from=NULL;
    char *call_id=ticket->sipmsg->call_id->number;
+   osip_authorization_t *auth=NULL;
 
 
    DEBUGC(DBCLASS_BABBLE, "entering blacklist_check");
@@ -293,6 +294,13 @@ static int blacklist_check(sip_ticket_t *ticket) {
    sql_stmt = NULL;
 
    if (MSG_IS_REGISTER(ticket->sipmsg)) {
+      /* Disarm initial REGISTER requests that carry no Authentication header data. */
+      /* So if no Auth Header is present, then set CALL-Id=<empty> */
+      if (osip_message_get_authorization(ticket->sipmsg, 0, &auth) < 0) {
+         DEBUGC(DBCLASS_BABBLE, "REGISTER without Auth data");
+         call_id="";
+      }
+
       /* Query 3: UPDATE OR IGNORE REGISTER request into requests DB */
       /* bind */
       sql_stmt = &sql_statement[SQL_CHECK_3];
@@ -328,7 +336,7 @@ static int blacklist_check(sip_ticket_t *ticket) {
    /* free resources */
    osip_free(from);
 
-   DEBUGC(DBCLASS_BABBLE, "leaving blacklist_check, UAC is permittet");
+   DEBUGC(DBCLASS_BABBLE, "leaving blacklist_check, UAC is permitted");
    return STS_SUCCESS;
 }