X.21
E1317165
UNEXPLORED
X.21 is a CCITT (ITU-T) standard defining a digital signaling interface for synchronous serial communication between data terminal equipment and data circuit-terminating equipment.
All labels observed (2)
How this entity was disambiguated
This entity first appeared as the object of triple T18293986 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: X.21 Context triple: [CCITT, notableStandard, X.21]
-
A.
X.25
X.25 is an early ITU-T packet-switched network protocol standard widely used for WAN communication before the rise of modern IP-based networks.
-
B.
EIA-232
EIA-232 is a standard for serial binary data communication that defines electrical and signaling characteristics for connecting data terminal equipment and data communication equipment.
-
C.
V.92
V.92 is an ITU-T modem standard that defines enhanced dial-up Internet connection features such as faster upload speeds, quicker call setup, and modem-on-hold capabilities.
-
D.
V.90
V.90 is an ITU-T modem standard that enabled dial-up internet connections at speeds up to 56 kbit/s over traditional telephone lines.
-
E.
ISDN
ISDN (Integrated Services Digital Network) is a set of communication standards for digital transmission of voice, video, and data over traditional telephone networks.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: X.21 Target entity description: X.21 is a CCITT (ITU-T) standard defining a digital signaling interface for synchronous serial communication between data terminal equipment and data circuit-terminating equipment.
-
A.
X.25
X.25 is an early ITU-T packet-switched network protocol standard widely used for WAN communication before the rise of modern IP-based networks.
-
B.
EIA-232
EIA-232 is a standard for serial binary data communication that defines electrical and signaling characteristics for connecting data terminal equipment and data communication equipment.
-
C.
V.92
V.92 is an ITU-T modem standard that defines enhanced dial-up Internet connection features such as faster upload speeds, quicker call setup, and modem-on-hold capabilities.
-
D.
V.90
V.90 is an ITU-T modem standard that enabled dial-up internet connections at speeds up to 56 kbit/s over traditional telephone lines.
-
E.
ISDN
ISDN (Integrated Services Digital Network) is a set of communication standards for digital transmission of voice, video, and data over traditional telephone networks.
- F. None of above. chosen
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.
linked to: X.21