State of knowledge

26 March 2024


The software is available as a preview version . There are still limitations in terms of functionality and quality. We are continuously working on further development.
The information provided here is still preliminary and is constantly being added to. 

System requirements

ProCall Enterprise

  • ProCall 8 Enterprise from version 8.4 
  • Active estos software maintenance contract (SPV
  • Release date of the UCServer used must not be older than 1 year.

ProCall mobility servíces

  • ProCall mobility services released on UCConnect.
  • Alternatively, a connection can be established with an activated web service on the UCServer and a certificate for HTTPS. 
    Encrypted communication with the UCServer Web Service must be available from the desktop workstation of the ProCall App for Web. 
    You can find out which ports you need to enable below under port enabling.

Supported web browsers

Current browser from desktop systems

  • Chromium-based browser
    • Google Chrome™ 
    • Microsoft® Edge
  • Mozilla Firefox® 
  • Apple Safari 

For example, the following are not supported:

  • Microsoft® Internet Explorer
  • Google Chrome or Mozilla Firefox on mobile devices such as with iOS
  • Old versions of Microsoft® Edge (without Chromium)
The ProCall App for Web does not support use on mobile devices such as smartphones or tablets with Android or iOS.
Alternatively, the ProCall mobile app (for Android/for iOS) can be used here.

as of 20/02/2024: Tested browser versions

The app has been successfully tested with the following browser versions:


Browser version

OS version

Google Chrome

120.0.6099.225 (64-Bit)

120.0.6099.234 (64-Bit)

Microsoft Windows 11, Windows 10

Apple macOS Sonoma (14.2.1 (23C71))

Mozilla Firefox121.0.1 (64-Bit)

Microsoft Windows 11, Windows 10

Apple Safari17.2.1 (18617., 18617)Apple macOS Sonoma (14.2.1 (23C71))
Microsoft Edge120.0.2210.144 (64-Bit)Microsoft Windows 11, Windows 10

Access to camera/microphone/notifications

The ProCall App for Web requires the following access options on the desktop system in order to be able to carry out the corresponding communication:

  • Access to microphone and, if necessary, camera for audio/video and softphone
  • Allow notifications and, if applicable, playing tones.

Port releases

The ProCall App for Web application runs as a website within a browser and is made available via the https protocol. This requires a release of the https port (443, outbound).
In summary, the most common port releases required for WebRTC are:

  • Ports 80 and 443 for Signaling
  • Port 3478 (UDP and TCP if applicable) for STUN
  • Port 5349 (TCP) for STUN via TLS
  • Ports für TURN-Relays, if required

Port number






to * (für Abruf der Anwendung)


TCPout(optional) Connection to the local UCWeb (not recommended)


TCP/TLSout(optional) Connection to the local UCWeb (secured)
3478UDP/TCPout(optional) to STUN/TURN Server
3478/443UDP/TCPout(optional) to * (for UCConnect services: STUN/TURN)
1024-65535 UDPin/outWebRTC Media (host candidates) from and to clients/media servers
(audio/video, softphone, screen sharing)


WebRTC (Web Real-Time Communication) is a technology that allows web applications to enable direct peer-to-peer communication for audio, video and data exchange without the need for plugins or external applications.
When setting up a WebRTC connection between two clients, the connection is usually established via several steps, which include so-called signaling and NAT traversal (NAT - Network Address Translation). 
The specific port releases for WebRTC vary.

Here are some of the key elements for WebRTC:

  • Signaling
    The first step, signaling, usually takes place via a central server (e.g. WebSocket, HTTP/HTTPS server), which is not part of the WebRTC protocol, but is necessary to exchange the connection information (SDP - Session Description Protocol) between the two clients. This server usually requires a port release for HTTP (port 80) or HTTPS (port 443).
  • STUN/TURN server
    WebRTC uses STUN (Session Traversal Utilities for NAT) and TURN (Traversal Using Relays around NAT) servers to support NAT traversal. These servers help to determine the public IP address and port of the client (STUN) or serve as a relay if a direct P2P connection is not possible due to firewall restrictions or complex NAT types (TURN).
    • STUN typically requires the UDP port 3478 and, if applicable, its TLS version requires the TCP port 5349.
    • TURN uses the same ports, but can also expect incoming connections on any UDP ports or TCP ports (if configured, e.g. port 80 or 443 for TCP), as TURN relays the data traffic for the clients.
  • Direct P2P connections 
    If a direct P2P connection is possible, the ports used can be selected randomly (random ephemeral ports). This selection depends on the local network restrictions and the availability of the ports.

Further information

ProCall App for Web

System requirements

ProCall App for Web – installation instructions – setup

Product page