How do i telnet into an avaya system?

If it is a G3 system, use the IP address and port 5111. If it is an ACM system S8300, S87xx, use port 5023. Try using Tuttytel, as it has some of the command codes needed for controlling the session. Simple telnet or hyperterminal lacks the terminal control codes (terminal type 513), and will just frustrate you. Access is controlled by an ID and password on most systems, by Avaya security guard ( a token pad protection scheme, like SecurID).