450
Summary
- // typical exposure
- Internal-only — CSTA/tserver is backend telephony call-control traffic linking a CTI application server to a PBX or Avaya AES server, with no documented reason to be reachable from the public internet.
- // common applications
- Avaya CT TSAPI Adapter Traffic on this port is most often CSTA/TSAPI call-control signaling between a CTI application server and an Avaya AES server; an Avaya CT TSAPI Adapter integration guide has been reported using port 450 as the default connection to query the AES server's TSAPI service-ID list.
- // analyst note
- An open 450/tcp outside a known Avaya/CTI telephony environment is unusual — verify it maps to a PBX/AES integration link before treating it as benign, since no other legitimate use is documented.
- // if you see it open
- No CVE or NVD record is associated with port 450 as of an August 2026 search, and the chebucto.ns.ca trojan-port reference table does not include it. As a CSTA/telephony-integration control-plane port linking a CTI application server to a PBX or Avaya AES server, it is not intended to be internet-facing and should be restricted to trusted internal network segments.
About port 450/tcp.
Port 450/tcp carries tserver, IANA's registration for CSTA (Computer Supported Telecommunications Applications) call-control traffic; it should stay on an internal network segment rather than face the public internet. IANA's own registry text spells the description "Computer Supported Telecomunication Applications" (singular, one m) — a registry-side spelling quirk for what the industry calls CSTA, an OSI standard maintained by ECMA International.
CSTA is an abstraction layer for computer-telephony integration (CTI): it lets an application control and monitor a telephone switch or PBX without needing that vendor's native signaling protocol. The specification became an OSI standard in July 2000 and is currently maintained by ECMA International.
IANA registers 450 as tserver on both TCP and UDP, with assignee/contact listed as [Harvey_S_Schultz] and a blank reference field — there is no RFC behind this assignment. No registration date is recorded, consistent with an older, informally-documented port assignment.
A re-research pass targeting the prior entry's application citations found that the Genesys T-Server "Supported Operating Environment" pages resolve but cover only operating systems, browsers, databases and virtualization — they never mention a port number — and every Xima Software Chronicall port-reference page returned HTTP 403 on direct fetch. Those two vendor associations are therefore dropped from the structured fields as unconfirmed; they may still be true, but no directly-readable page currently supports the port-450 claim.
One vendor document was found that does state the port directly: an Avaya CT TSAPI Adapter integration guide describes the default TSAPI connection as being on port 450, used to query the list of TSAPI service IDs on an Avaya Application Enablement Services (AES) server. This is treated as a single-source, hedged finding rather than a confirmed fact.
nmap-services open-frequency data puts 450/tcp at roughly 0.005% and 450/udp at roughly 0.07% — both rare, consistent with a niche enterprise-telephony port rather than a widely-run service.
- IANA assignment
tserver— "Computer Supported Telecomunication Applications" (registry's own spelling; industry/ECMA standard name is Computer Supported Telecommunications Applications, CSTA); reference (blank — no RFC cited in IANA registry); assignee/contact [Harvey_S_Schultz]; dual-registered 450/tcp + 450/udp[Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry tserver 450/tcp, tserver 450/udp- Range class
- well-known (0–1023); source artifact labels this the "system" range [Confirmed] — this site's own tooling (port 450 entry)
- Prevalence
- nmap-services open-frequency 450/tcp ≈ 0.00005 (~0.005%); 450/udp ≈ 0.000692 (~0.07%) [Confirmed] — this site's own tooling (port 450 entry)
- Related ports
- 2050/tcp+udp
av-emb-config(Avaya EMB Config Port) — adjacent Avaya-ecosystem IANA registration [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry av-emb-config 2050/tcp
Primary use
CSTA (Computer Supported Telecommunications Applications) — a CTI abstraction/call-control layer letting applications control and monitor PBX/ACD telephone switches independent of the underlying vendor protocol; became an OSI standard in July 2000, currently maintained by ECMA International [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv, https://en.wikipedia.org/wiki/Computer-supported_telecommunications_applications
Other/unofficial uses
an Avaya CT TSAPI Adapter integration guide states port 450 is the default connection used to query an Avaya AES server's TSAPI service-ID list; Genesys T-Server and Xima Chronicall associations reported by prior research could not be re-confirmed on direct fetch and are not asserted here
Security implications
no CVE/NVD record as of an August 2026 search; the chebucto.ns.ca trojan-port reference list does not include port 450; CSTA/telephony control-plane traffic should stay restricted to trusted internal segments between the PBX/AES server and the CTI application server
Typically seen on
enterprise telephony/CTI environments running Avaya AES infrastructure with a TSAPI integration adapter (e.g. Avaya CT TSAPI Adapter) querying the TSAPI service list
- Analyst note
- An open 450/tcp outside a known Avaya/CTI telephony environment is unusual — verify it maps to a PBX/AES integration link before treating it as benign, since no other legitimate use is documented.
About port 450/udp.
Port 450/udp carries tserver, IANA's registered name for CSTA-style telephony integration; it should stay off the public internet, since its only identified real-world tie is legacy, internal enterprise telephony-server infrastructure with no design intent for internet-facing exposure.
IANA's Service Name and Transport Protocol Port Number Registry lists port 450 as tserver on both tcp and udp, described as "Computer Supported Telecomunication Applications," assigned to [Harvey_S_Schultz], with the Reference, Registration Date, and Modification Date fields all blank — no RFC underlies this assignment.
Wikipedia's TSAPI page confirms the general background: Novell and AT&T co-developed TSAPI (Telephony Server Application Programming Interface), a CTI standard, and Novell shipped TServer as its telephony-server component, running on NetWare and bridging to PBX/telephony switches via brand-specific drivers. Wikipedia itself does not mention port 450.
Independent of Wikipedia, community-sourced TSAPI client configuration files (TSAPI.PRO / tsapi.pro properties files distributed with TSAPI/JTAPI CTI client libraries) explicitly document port 450 as the default TServer connection port — sample entries include "tserver.mydomain.com=450" and IP-address:450 server lines, including one Avaya AES CSTA telephony-link example. Two independently archived samples (a GitHub jdial project file and an archived Cornell CS519 course file) show the same convention, though neither is a first-party Novell/OpenText or Avaya statement, so the tie is hedged.
No current, actively-maintained software was found reported as using 450/udp as of an August 2026 search, and no forum, blog, or vendor-support thread named a different modern application. SANS ISC's port-450 activity page shows only low-volume background internet scanning, consistent with routine sweep noise rather than active exploitation or targeted use.
- IANA assignment
tserver— "Computer Supported Telecomunication Applications" (verbatim registry spelling); reference blank (no RFC cited); assignee/contact [Harvey_S_Schultz]; dual-registered 450/tcp + 450/udp[Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry tserver 450/tcp, tserver 450/udp- Range class
- well-known (0–1023); source artifact labels this the "system" range [Confirmed] — this site's own tooling (port 450 entry)
- Prevalence
- nmap-services open-frequency 450/udp ≈ 0.000692 (~0.07%); 450/tcp ≈ 0.00005 (~0.005%) [Confirmed] — this site's own tooling (port 450 entry)
- Related ports
- 450/tcp (dual IANA registration, same
tservername) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry tserver 450/tcp
Primary use
corresponds to the CSTA (Computer Supported Telecommunications Applications) telephony-integration standard; Wikipedia's TSAPI page confirms Novell/AT&T co-developed TSAPI and that Novell's TServer component ran on NetWare bridging to PBX switches, but does not itself name port 450; independent community-sourced TSAPI client config files (TSAPI.PRO/tsapi.pro) document port 450 as the default TServer connection port [Likely] — https://en.wikipedia.org/wiki/Telephony_Server_Application_Programming_Interface, https://github.com/juradoz/jdial/blob/master/jdial-cti/src/main/resources/TSAPI.PRO, http://www.cs.cornell.edu/courses/cs519/1998fa/project/Software/tsapi.pro
Other/unofficial uses
none identified beyond the TSAPI/TServer tie above [Unknown]
Security implications
no CVE/NVD record as of an August 2026 search; SANS ISC reports only low-volume background scanning; auditmypc.com's negative "Virus/Trojan: No" verdict is the only malware-association data point found
Typically seen on
legacy Novell NetWare / TSAPI (Telephony Server API) telephony-integration environments, per hedged community config-file attribution (not a first-party vendor statement); no confirmed modern deployments as of an August 2026 search [Likely] — https://github.com/juradoz/jdial/blob/master/jdial-cti/src/main/resources/TSAPI.PRO, http://www.cs.cornell.edu/courses/cs519/1998fa/project/Software/tsapi.pro
- Analyst note
- An open 450/udp has no confirmed modern legitimate use; because its only identified tie is to legacy internal NetWare/TSAPI telephony infrastructure, treat an internet-reachable listener as unexpected and worth investigating.
Service assignments.
| Name | Protocol | Description | Open frequency |
|---|---|---|---|
| tserver | UDP | — | 0.07% |
| tserver | TCP | Computer Supported Telecomunication Applications | 0.01% |
Service assignments from the IANA Service Name and Transport Protocol Port Number Registry, with open-frequency data from nmap-services.