diff --git a/library/SIP_Templates.ttcn b/library/SIP_Templates.ttcn
index f48d137..fc8e23f 100644
--- a/library/SIP_Templates.ttcn
+++ b/library/SIP_Templates.ttcn
@@ -525,6 +525,26 @@
 	payload := omit
 }
 
+/* Expect during first REGISTER when authorization is required: */
+template (present) PDU_SIP_Response
+tr_SIP_Response_REGISTER_Unauthorized(
+	template CallidString call_id,
+	template SipAddr from_addr,
+	template SipAddr to_addr,
+	template (present) Via via := tr_Via_from(?),
+	template Contact contact := *,
+	template integer seq_nr := ?,
+	template charstring method := "REGISTER",
+	template integer status_code := 401,
+	template charstring reason := "Unauthorized",
+	template charstring body := *) := {
+	statusLine := tr_SIP_StatusLine(status_code, reason),
+	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, contact,
+				     via,
+				     method, *, seq_nr),
+	messageBody := body,
+	payload := omit
+}
 
 /* RFC 3261 8.1.1.5:
  * "The sequence number value MUST be expressible as a 32-bit unsigned integer