Detects the UDP IAX2 service.
The script sends an Inter-Asterisk eXchange (IAX) Revision 2 Control Frame POKE request and checks for a proper response. This protocol is used to enable VoIP connections between servers as well as client-server communication.
nmap -sU -sV -p 4569 <target>
PORT STATE SERVICE VERSION 4569/udp closed iax2
License: Same as Nmap--See https://nmap.org/book/man-legal.html