SIP call between ProCall App for Web and ProCall Enterprise Client for Windows within a LAN

Scenario

• An estos ProCall Enterprise Softphone Client for Windows calls an estos ProCall App for Web Client on its SIP subscriber line via its SIP subscriber line.
• Both call partners communicate via this connection.
• Both estos ProCall clients are in the same local network.
• Both users with estos ProCall clients work on the same estos ProCall Enterprise Server.

Explanations

For SIP calls from or to an estos ProCall Enterprise Softphone Client for Windows, the estos UC Media Server is always involved as an audio relay between the client and the telephone system.
This means that the media streams are always routed via the estos UC Media Server.

Call controlling as well as messaging for this SIP call always takes place via the estos UCServer, which mediates between the client and the telephone system.

An estos ProCall Enterprise Client is never in direct communication with the telephone system.

Media connection via the PBX gateway

Diagram/topology: PBX - UCServer service - ProCall clients - SRTP audio/video

The topology diagram shows a typical ProCall Enterprise installation in the LAN (local network), assuming unrestricted communication between all clients and ProCall Enterprise Server .

The ProCall clients establish a connection to ProCall Enterprise Server port 7222 (in the installation standard) via a dynamically assigned TCP port .
The clients use this connection to exchange requests and events with the server in order to process telephony events or carry out telephony activities.

For the exchange of RTP media packets during a SIP call, each client negotiates a direct connection via ICE handshake with the estos UC Media Server via UDP(WebRTC standard).
Ports from the range 1024 to 65535 are used (all ports with the exception of the well-known ports). If the entire port range should not or cannot be used, it is possible to limit the media port range (min/max) in the UCServer administration under the settings for the line group. This setting option currently only affects the estos ProCall Enterprise Client for Windows, but not the estos ProCall App for Web.

The exchange of RTP media packets between estos UC Media Server and the telephone system is agreed in the SDP exchanged between these components.

Firewall-Regeln

Die hier aufgeführten Firewall-Regeln stellen die Minimalanforderungen dar, die ohne spezifische Kenntnisse der jeweiligen Umgebung angenommen werden können.

Media connection in direct media mode

As shown in the diagram above, a media stream from a client is routed via the server to the telephone system, the telephone system routes this media stream back to the server, which then feeds it to the second client. Depending on the technical possibilities of the telephone system, the paths of the media streams between the estos ProCall clients can also be shortened in this scenario. Some telephone systems recognise that the media streams between the communication participants can also be exchanged directly, i.e. they do not have to be routed through the PBX Voice Gateway. In this case, the telephone system signals the estos ProCall Enterprise Server in the SDP as the source and destination for audio and the estos UC Media Server no longer sends the media streams to the telephone system, but to itself(loopback). Depending on the telephone system, this technology is described under a term such as direct media, direct routing or media bypassing. This changes the representation of the media streams as follows:

Diagram/topology: PBX - UCServer service - ProCall clients - SRTP audio/video - Direct Media operation

Firewall rules

The firewall rules required for these communication relationships remain unchanged:

In order to record the media streams on the estos ProCall Enterprise Server in Direct Media mode for analysis purposes (capturing), the loopback network adapter must also be included in the capturing.

Further information

• ProCall App for Web - System requirements - Port releases
• Release ports for estos products - Which network interfaces are used?