State of knowledge

May 2024

This overview delivers information about estos ProCall Enterprise supported features

  • operating on SIP devices via estos uaCSTA Server and estos ECSTA for SIP Phones (TAPI)
  • SIP softphone operations via direct SIP communication to the PBX (SIP).
ProCall EnterpriseV 8.5
PBX/Cloud PBXMitel MiVoice Business from V 9.1
with device/telephoneMitel end devices
TSPECSTA for Mitel MiVoice Business


ProCall Enterprise Client for Windows

ProCall Mobile App ***





Hang up

Answer call

Hold call


Retrieve conversation

Reject call

Forward call (without answering)


Forward call (after answering)


Set up consultation call


Connect consultation call

Initiate second call (e.g. from Hold)

Accept second call

Reject second call

Forward second call (without answering)

Forward second call (after answering)

Second call on SIP line

caller receiving busy

caller receiving busy

Incoming call on SIP Line while active mobile phone call:

  • Answer call

mobile phone call is terminated

mobile phone call on hold **

  • Reject

caller receiving busy

Incoming mobile phone call while active SIP line call:

  • Answer call

SIP line call on hold

SIP line call on hold

  • Reject

Create conference (3 participants)

Add further participant to conference call

Remove participant from conference call

Pickup call


  • TAPI – SIP 

  • SIP – TAPI (via UCServer)

  • SIP – SIP (via UCServer)


Dial ringing tone

Call forwarding

  • Provided by PBX via TAPI

  • via feature code

  • provided by UCServer


Do not disturb

  • via presence

  • via line


Function available
Availability or function planned
Not relevant
Not applicable due to technical limitations
Function not tested, full tests are pending
*1If the call is forwarded to a busy/DND subscriber, the caller hears a dial tone.
*2If an attempt is made to forward the call to a busy/DND subscriber, the call is not put through.
**depending on the functions of the network provider
***Supported functions for SIP lines in ProCall Mobile Apps for connection via estos UCConnect

Hinweis zum Zweitanruf

With the Mitel MiVoice Business telephone system, second calls cannot be controlled via TAPI.
We recommend deactivating the second call for Mitel telephone terminals.

To do this, go to  System Feature Settings - Class of Service Options in User Profile under "Campon" disable the option "External Campon Allowed" .

The setting only affects Mitel end devices. The SIP lines still have the "second call" function in full. 

Version info

Since estos has no influence on the further development of the supported telephone systems by the manufacturer, we cannot guarantee that the manual described above is also valid for future releases and e.g. other end devices without restrictions.

Further information

Telefonanlagen-spezifische Konfiguration: Softphone Funktionen (SIP) für Mitel MiVoice Business einrichten - Anschalthinweise

ProCall 8 Enterprise – softphone functionality

SIP user registration on the PBX/vPBX