[Serusers] Preventing unregistered users from calling

Hello, I wanted to configure ser so that only registered user are allowed to make calls. I have set up digest authentication but still unregistered users can make calls. I wonder if I'm missing something on my config file (as attached below). Could someone please tell me what am I doing wrong, or provide me some configuration example on solving this issue? Thanks and regards, Claudio ########### ser.conf ########### route{ # Do strict routing if pre-loaded route headers present rewriteFromRoute(); if (uri==myself) { if (method=="REGISTER") { if (!www_authorize("<my_ip>", "subscriber")) { www_challenge("<my_ip>", "0"); break; }; if (method=="INVITE" & !check_from()) { sl_send_reply("403","Forbidden"); break; }; save("location"); break; }; # native SIP destinations are handled using our USRLOC DB if (!lookup("location")) { sl_send_reply("404", "Not Found"); break; }; }; # forward to current uri now if (!t_relay()) { sl_reply_error(); }; } ##########