/* Handle authentication if this is our first subscribe */
                res = check_user_full(p, req, SIP_SUBSCRIBE, e, 0, sin, ignore, mailbox, sizeof(mailbox));
                if (res) {
                        if (res < 0) {
                                ast_log(LOG_NOTICE, "Failed to authenticate user %s for SUBSCRIBE\n", get_header(req, "From"));
                                ast_set_flag(p, SIP_NEEDDESTROY);
                        }
                        return 0;
                }