View source for H.450

{{Short description|International Telecommunication Union standards}}
'''H.450''' refers to a set of standards created by the [[International Telecommunication Union]] (ITU) to define several Supplementary Services of the packet based telecommunication protocol known as [[H.323]].<ref name="n507">{{cite book | last=Swale | first=Richard | title=Voice Over IP (Internet Protocol) | publisher=IET | publication-place=London | date=2001-12-17 | isbn=978-0-85296-024-0 | page=254}}</ref> It parallels another set of standards known as [[QSIG]] which define similar services for [[ISDN]] based networks.

==Standards==

* '''H.450.1''', Supplementary Services Framework<ref name="q185">{{cite web | title=H.450.1 Generic functional protocol for the support of supplementary services in ITU-T H.323 systems | website=ITU | url=https://www.itu.int/rec/T-REC-H.450.1/en | access-date=2025-07-24}}</ref>
The general mechanism for delivering supplementary services is explained in this paper. Supplementary services messages are exchanged by means of ROSE (Remote Operations Service Extension).

* '''H.450.2''', [[Call transfer|Call Transfer]] Supplementary Service<ref name="b224">{{cite web | title=H.450.2 Call transfer supplementary service for ITU-T H.323 systems | website=ITU | date=2014-05-15 | url=https://www.itu.int/rec/T-REC-H.450.2 | access-date=2025-07-24}}</ref>
E.g. explains how a party-B can turn an active call between party-A and party-B into a call between party-A and a new party-C.

* '''H.450.3''', Call Diversion Supplementary Service
E.g. explains how an IP phone can activate a diversion to e.g. a cell phone.
E.g. explains how an IP phone can interrogate whether it has any active diversion.

* '''H.450.4''', Call Hold Supplementary Service 
E.g. explains how a call can be put on hold and be fed with a music on hold.

* '''H.450.5''', Call Park and Pickup Supplementary Service
Think of big warehouse, where a call is coming in at the front-desk for Mrs. Smith.
The front-desk parks the call and broadcasts via the intercom: "Mrs. Smith, please 223".
Mrs. Smith proceeds soon after to the next wall phone, dials 223 and gets the call.

* '''H.450.6''', [[Call waiting|Call Waiting]] Supplementary Service 
Explains how to signal a second call to an IP phone already engaged in an active call.

* '''H.450.7''', Message Waiting Indication Supplementary Service 
Explains elements related to voicebox systems and how these can be implemented by means of H.323.

* '''H.450.8''', Name Identification Supplementary Service 
Explains how names are displayed or how to intentionally call incognito.

* '''H.450.9''', Call Completion Supplementary Service 
Explains how to schedule an automatic call-back request in case of a remote party being busy in a call or being absent for a while and becoming available later on.

* '''H.450.10''', Call Offer Supplementary Service 
A variation of Call Waiting. Also known as "Camp-On".

* '''H.450.11''', Call Intrusion Supplementary Service
Explains how e.g. the secretary of a CEO can intentionally and legally intrude into a call of her boss, in order to communicate urgent information.

* '''H.450.12''', Common Information Additional Network Feature for H.323
A means to communicate additional miscellaneous information between endpoints. E.g. whether certain features are available, and/or allowed.

==References==
{{Reflist}}

[[Category:ITU-T recommendations]]