diff -NaurbB old/chan_sip.c new/chan_sip.c
--- old/chan_sip.c	2009-02-04 14:58:16.000000000 +0000
+++ new/chan_sip.c	2009-02-12 12:15:09.000000000 +0000
@@ -220,7 +220,8 @@
 #define MAX(a,b) ((a) > (b) ? (a) : (b))
 #endif
 
-#define CALLERID_UNKNOWN        "Unknown"
+#define CALLERID_UNKNOWN        "Anonymous"
+#define FROMDOMAIN_INVALID	"anonymous.invalid"
 
 #define DEFAULT_MAXMS                2000             /*!< Qualification: Must be faster than 2 seconds by default */
 #define DEFAULT_QUALIFYFREQ          60 * 1000        /*!< Qualification: How often to check for the host to be up */
@@ -8791,6 +8792,7 @@
 	char tmp_l[SIPBUFSIZE/2];	/* build a local copy of 'l' if needed */
 	const char *l = NULL;	/* XXX what is this, exactly ? */
 	const char *n = NULL;	/* XXX what is this, exactly ? */
+	const char *d = NULL;	/* domain in from header */
 	const char *urioptions = "";
 
 	if (ast_test_flag(&p->flags[0], SIP_USEREQPHONE)) {
@@ -8815,6 +8817,7 @@
 
 	snprintf(p->lastmsg, sizeof(p->lastmsg), "Init: %s", sip_methods[sipmethod].text);
 
+	d = S_OR(p->fromdomain, ast_inet_ntoa(p->ourip.sin_addr));
 	if (p->owner) {
 		l = p->owner->cid.cid_num;
 		n = p->owner->cid.cid_name;
@@ -8824,6 +8827,7 @@
 	    ((p->callingpres & AST_PRES_RESTRICTION) != AST_PRES_ALLOWED)) {
 		l = CALLERID_UNKNOWN;
 		n = l;
+		d = FROMDOMAIN_INVALID;
 	}
 	if (ast_strlen_zero(l))
 		l = default_callerid;
@@ -8849,9 +8853,9 @@
 	}
 
 	if (!sip_standard_port(p->socket) && ast_strlen_zero(p->fromdomain))
-		snprintf(from, sizeof(from), "\"%s\" <sip:%s@%s:%d>;tag=%s", n, l, S_OR(p->fromdomain, ast_inet_ntoa(p->ourip.sin_addr)), ntohs(p->socket.port), p->tag);
+		snprintf(from, sizeof(from), "\"%s\" <sip:%s@%s:%d>;tag=%s", n, l, d, ntohs(p->socket.port), p->tag);
 	else
-		snprintf(from, sizeof(from), "\"%s\" <sip:%s@%s>;tag=%s", n, l, S_OR(p->fromdomain, ast_inet_ntoa(p->ourip.sin_addr)), p->tag);
+		snprintf(from, sizeof(from), "\"%s\" <sip:%s@%s>;tag=%s", n, l, d, p->tag);
 
 	/* If we're calling a registered SIP peer, use the fullcontact to dial to the peer */
 	if (!ast_strlen_zero(p->fullcontact)) {