Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 144759)
+++ channels/chan_sip.c	(working copy)
@@ -189,6 +189,8 @@
 
 #define XMIT_ERROR		-2
 
+#define SIP_RESERVED ";/?:@&=+$,# "
+
 /* #define VOCAL_DATA_HACK */
 
 #define DEFAULT_DEFAULT_EXPIRY  120
@@ -6113,6 +6115,18 @@
 		if (authuser)
 			*authuser++ = '\0';
 	}
+	if (strsep(&username, SIP_RESERVED)) {
+		ast_log(LOG_WARNING, "Reserved character '%c' used in username portion of register line. We will not send REGISTER for this user\n", *username);
+		return -1;
+	}
+	if (!ast_strlen_zero(secret) && strsep(&secret, SIP_RESERVED)) {
+		ast_log(LOG_WARNING, "Reserved character '%c' used in secret portion of register line. We will not send REGISTER for this user\n", *secret);
+		return -1;
+	}
+	if (!ast_strlen_zero(authuser) && strsep(&authuser, SIP_RESERVED)) {
+		ast_log(LOG_WARNING, "Reserved character '%c' used in authuser portion of register line. We will not send REGISTER for this user\n", *authuser);
+		return -1;
+	}
 	/* split host[:port][/contact] */
 	callback = strchr(hostname, '/');
 	if (callback)