--- chan_sip.c  2005-06-24 17:53:02.000000000 -0400
+++ chan_sip-l3.c       2005-11-02 16:11:29.000000000 -0500
@@ -7274,8 +7274,10 @@
                /* XXX Should we authenticate OPTIONS? XXX */
                if (ast_strlen_zero(p->context))
                        strncpy(p->context, default_context, sizeof(p->context) - 1);
-               if (res < 0)
+               if (res < 0) {
+                       transmit_response(p, "100 Trying", req);
                        transmit_response_with_allow(p, "404 Not Found", req, 0);
+               }
                else if (res > 0)
                        transmit_response_with_allow(p, "484 Address Incomplete", req, 0);
                else