State of knowledge

April 2024

optimized for 2 to 2500 users

Operating systems and databases


Supports 64-bit Microsoft Windows systems

Server operating systems

End date for support

Microsoft Windows Server® 202213/10/2031

Microsoft Windows Server® 2019


Microsoft Windows Server® 2016


.NET Framework 4.8

Please note that a .NET Framework 4.8 must be available to operate the UCServer. This must be installed in advance on older systems < Windows Server 2022. .NET Framework versions and dependencies

Software virtualization

  • Microsoft Hyper-V
  • VMware Horizon (VDI)

ProCall client for Windows

Client/workstation operating systems

End date for support

Microsoft Windows® 11-

Microsoft Windows® 10 (from version1903)  (warning) 


Chat in ProCall 8 Enterprise for ProCall client for Windows

Chat in ProCall 8 Enterprise

Optional for "VPN-less" connection

see system requirements under Connect ProCall for Windows easily via the internet ("VPN-less")


Support for 3 years after release (older or in Google Play Store required minimum Android versions may still work. may still work,  but no support is provided).

Operating system

End date for support

Android 143 years after release – 8/2026
Android 133 years after release – 8/2025
Android 123 years after release – 10/2024


Support of the current and the previous version (older OS versions may possibly still work, but no support is given).

Operating system

End date for support

iOS 17*3 months after release of iOS18 (expected 12/2025)
iOS 16 *3 months after release of iOS18 (expected 12/2024)

* estos recommends the use of the latest Apple security updates.


Support of the current and the previous version (older OS versions may possibly still work, but no support is given).

Operating system

End date for support

macOS 14 "Sonoma"3 months after release of macOS 16 (expected 12/2025)
macOS 13 "Ventura"3 months after release of macOS 15 (expected 12/2024)




Editions (info)

End date for support

Microsoft SQL Server 2022 

  • for ProCall 8 Enterprise from UCServer Version 8.2.1 on


Microsoft SQL Server 2019

Enterprise, Standard 


Microsoft SQL Server 2017

Enterprise, Standard


Microsoft SQL Server 2016 Service Pack 2Enterprise, Standard, 


Microsoft SQL Server 2014 Service Pack 3

Enterprise, Standard


Integrated in ProCall Enterprise; cannot be used in combination with other applications such as ProCall AnalyticsSQLiteLike ProCall 8 Enterprise

The use of Microsoft SQL Server Express is outdated

Please see the following article: (warning) Limitations when using Microsoft SQL Server Express

Scaling limits

For the selection of the appropriate database connection, the following overview serves as a guide, which has to be defined in addition to the scaling limits of active ProCall Enterprise users or simultaneous calls (which was applicable earlier):

Up to 250 usersUp to 10,000 users (blue star)From 10,000 users (blue star)
SQL Server Express (warning),
SQLite (integrated in ProCall 8 Enterprise)
SQL Server Standard, 2 CoreSQL Server Enterprise, 4 Core (Minimum)

(blue star) Multiple UCServer with separate databases, each with a maximum of 2,500 users per UCServer installation.

When selecting the appropriate Microsoft SQL Server Edition, the scale limitations of the databases must be taken into account and the configuration must be made accordingly in ProCall Enterprise and in the SQL Server. The scale limits of Microsoft SQL Server can be found in the following article Editions and supported features of SQL Server 2019 (15.x). For further planning, the following article can be used as a starting point: Planning an SQL Server Installation.

Notes on the General Data Protection Regulation (GDPR)

Personal data (e.g. journal information) is stored in the database. Please note that this may require authorization under data protection law.

Internet connection and network interfaces/ports

For ProCall 8 Enterprise a persistant and stable internet connection between UCServer and estos UCConnect is required.

See Release ports for estos products – which network interfaces are used?

Connection from UCConnect Portal: UCServer



Source portall
Destination port:443 TCP


Licenses for ProCall 8 Enterprise

Online licensing of ProCall 8 Enterprise

Hardware recommendation for system expansion (minimum)


  • Active users: 50
  • CPU*: 2 Core, 1,9 GHz
  • RAM: 8 GB
  • Hard disk: 10 GB
  • Network: 50 Mbit/s

* Processor needs SSE support

System requirements – detailed instructions for suitable system expansion

The number of logged-in users, monitored lines and presences and active softphone calls influence the hardware requirements for the UCServer and the number of media servers.

Here you will find hints and tips for a suitable system design.

Windows client workstation

  • CPU: 2 Core, 2 GHz
  • RAM: 150 MB
  • Hard disk: 300 MB
  • Network: 50 Mbit/s

Scalability/redundancy/multi-server environment

Find more information at ProCall DataCenter

Supported third-party products/interoperability

For further information on supported third-party products and interoperability details for e.g. groupware systems, headsets, telephone systems, please click here:

ProCall Enterprise: Supported third-party products

Supported cryptographic algorithms (ciphers)

Restrictions for Microsoft Windows® 10 versions

Please refer to our Notes on Microsoft Windows 10 operating system support and version changes.