:OpenStage CTI Applications

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CTI allows a computer to interact with the telephone, e.g. in setting up and terminating calls with numbers taken from a directory via a PC application.

There are basically two different approaches supported with CTI:

  • The computer (e.g. a PC located at the same desk as the telephone) directly interacts with the telephone (First Party CTI).
  • The computer (could also be a co-located PC) interacts with the telephone system (e.g. SIP application server), and the latter controls the telephone: Third Party CTI.

OpenStage telephones are able to support Third Party CTI. First Party CTI will be supported in the future.

For Users

First party CTI

Not supported.

Third party CTI

Third party CTI is a telephony system driven feature. The communication is done between the computer application and the telephone system. The user can configure the treatment of CTI Calls on the phone.

The setting can be done at the user part of phone via WBM or local user access. The parameters can be found at:

User->Configuration->Incoming Calls->CTI calls in the user menu.

There are three parameters to change the CTI call treatment:

  • Allow auto-answer
  • Allow beep on auto-answer
  • Allow beep on auto-reconnect

Allow auto-answer

This setting defines whether or not incoming calls are automatically accepted.
The phone will automatically enter the free speaking mode, if a call is initiated by an CTI application (such as Outlook). If a headset is plugged in, the phone will activate the headset for the CTI call. All other incoming calls will still cause a ringing tone.

Allow beep on auto-answer

If the function is active, an alert beep sounds when a call is automatically accepted. Allow auto-answer must be set to on. Prerequisite: The option was programmed by your administrator.

Allow beep on auto-reconnect

You can reconnect a held call both via the CTI application and via the phone. A beep sounds when you toggle between an active call and a held call when the function is active. Prerequisite: The option was programmed by your administrator.

For Administrators

First party CTI

Not supported.

Third party CTI

The OpenStage SIP phones support two different CTI control protocol.

  • 3rd party call control via SIP

The phone is supporting the RFC 3725 - Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP). To trigger the auto answer mode of the phone the appropriate Alert Info Header must be set. Example:

Alert-Info: <>;info=alert-autoanswer

  • uaCSTA

User Agent CSTA (uaCSTA) is a limited subset of the CSTA protocol, which allows external CTI applications to interact with the phone.

Tha uaCSTA control for the Administrator can be found at:


Allow uaCSTA

If Allow uaCSTA is enabled, applications which support the uaCSTA standard will have access to the OpenStage phone. The default is "Yes".

Technical Background


See also