Merged revisions 188646 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r188646 | dvossel | 2009-04-15 17:08:40 -0500 (Wed, 15 Apr 2009) | 12 lines
  
  National prefix inserted even when caller ID not available
  
  When the caller ID is restricted, the expected behavior is for the caller id to be blank.  In chan_dahdi, the national prefix is placed onto the callers number even if its restricted (empty) causing the caller id to be the national prefix rather than blank.
  
  (closes issue #13207)
  Reported by: shawkris
  Patches:
        national_prefix.diff uploaded by dvossel (license 671)
  
  Review: http://reviewboard.digium.com/r/220/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@188647 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_dahdi.c

@@ -11323,6 +11323,12 @@ static void ss7_start_call(struct dahdi_pvt *p, struct dahdi_ss7 *linkset)
 #if defined(HAVE_SS7)
 static void ss7_apply_plan_to_number(char *buf, size_t size, const struct dahdi_ss7 *ss7, const char *number, const unsigned nai)
 {
+	if (ast_strlen_zero(number)) { /* make sure a number exists so prefix isn't placed on an empty string */
+		if (size) {
+			*buf = '\0';
+		}
+		return;
+	}
 	switch (nai) {
 	case SS7_NAI_INTERNATIONAL:
 		snprintf(buf, size, "%s%s", ss7->internationalprefix, number);
@@ -12347,6 +12353,12 @@ static void apply_plan_to_number(char *buf, size_t size, const struct dahdi_pri
 		snprintf(buf, size, "%s", number);
 		return;
 	}
+	if (ast_strlen_zero(number)) { /* make sure a number exists so prefix isn't placed on an empty string */
+		if (size) {
+			*buf = '\0';
+		}
+		return;
+	}
 	switch (plan) {
 	case PRI_INTERNATIONAL_ISDN:		/* Q.931 dialplan == 0x11 international dialplan => prepend international prefix digits */
 		snprintf(buf, size, "%s%s", pri->internationalprefix, number);