ZyXEL Communications Prestige 128 Plus User Manual page 124

Prestige 128+ ISDN Router
Services
FTP (File Transfer Protocol)
Telnet
SMTP (Simple Mail Transfer Protocol)
DNS(Domain Name System)
HTTP (Hyper Text Transfer protocol or WWW, Web) 80
PPTP (Point-to-Point Tunneling Protocol)
8-14
Port Number
21
23
25
53
1723
Dial-In Server Configuration