answer_machine.pl

* answer machine which can play a welcome message and
  record calls
* can handle multiple calls in parallel

stateless_proxy.pl

* not so simple stateless proxy which will forward
  SIP packets between legs
* can forward based on destination domain
* can have registrars on legs and forward to registered
  clients
* can do NAT either in-process or together with 
  nathelper.pl 

nathelper.pl 

* standalone process to rewrite proxy RTP connections
* works together with stateless_proxy.pl or anything else
  which uses Net::SIP::NATHelper::Server