11.7  Safe access to headers

   1 service boss_secretary {
       processing {
         dialog {
           response outgoing INVITE(request rq) {
   5         if (TO == 'sip:my.boss@big-corp.com') {
               response x = forward;
               select (x) {
               case /ERROR:
                 when rq (#subject: string sub) {
  10               rq = rq with {#subject: "The boss is unavailable ! - "+ sub};
                 }
                 when x (#contact: uri r_contact) {
                   if (r_contact != CONTACT) {
                     return forward r_contact;
  15               }
                 }
                 return forward 'sip:boss.secretary@big-corp.com';
                   
               case /SUCCESS: return x;
  20           }
             }
             else {
               return forward;
     } } } } }