Case 8000 Series Reference Manual page 101

<TCP port>
A TCP port is a number in the range 0 to 65535 (16 bits). The port refers
to a logical device within a physical device (Internet Address). This
number is often translated into a service, e.g. 23 is commonly used for
the TELNET service on hosts that support TCP/IP.
<X.121 Address>
An X.121 address is a 14-digit address which will be interpreted by the
Series 8000 PSE in the following way:
Digits 1-4
Digits 5-7
Digits 8-11
Digits 12-14 (000-999) the Subaddress field.
X870-300351 Issue 1
DNIC – 1100 is the Series 8000 default DNIC (Data
Network Identification Code).
(000-999) the Series 8000 Node Number.
(0000-9999) the Logical Port Number of the port to which
the calling or called device is connected.
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