Chorus network preparation

Network preparation for Chorus

Before you can use Chorus telephones on your site there will be some changes that need to take place within your unit's local network.

There are two ways a unit can adopt the Chorus service – using either converged or separated networking. Both options are described in detail below.

Each Frodo should already have an access port for your data connection, but as part of the preparation a separate Chorus access port will be enabled on your Frodo.

You can use whatever vlan number you want internally, but using 341 would make it easier to set up DECT and Polycom phones.

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The first step before configure individual ports is to setup the VLAN for Chorus (this can be any VLAN number) to create a port to be connected to the FroDo's Chorus port.

A converged network is one where all of your network ports can be used for voice and data connections because the edge switches are setup to recognise if a phone or a computer is connected. This is done through the addition of a voice VLAN and some QoS settings.

The diagram below assumes that you are using VLAN 100 for your internal data network and that you have created a new Chorus voice network on VLAN 200. In this scenario your internal main switch (switch 1 in the graphic) is configured to understand both VLAN 100 and 200, and it must present these two VLANs as two separate access ports (not trunk ports) as uplinks to the Frodo.

To deliver the Chorus voice network to other downstream switches, the trunk ports between switch 1 and 2, and beyond, will need to be 'tagged' to include voice VLAN 200 alongside VLAN 100.

On Switch 2 you could have a mix of purely access ports for data and voice, or hybrid ports. Most modern switches support hybrid ports nowadays. A hybrid port is recommended – as it will carry the data traffic as untagged and any voice traffic as tagged (hence "converged network").

Below are some example converged switch port configs for various manufacturers. These ports are also known as 'hybrid' ports. Your switches would also need to be setup for QoS as the voice traffic is sharing network ports and switch trunk links with the data network, there is more QoS information further on in this guide.


​​Option for switches without LLDP/LLDP-MED capabilities


If there are enough patch ports at the require location then separating the phone network and using 'access' ports which don't require LLDP to function is an option, see below for details on a separated network.

If you choose to operate two physically separated internal networks for the services you provide you can have switches and Ethernet points dedicated solely to telephony, while others are reserved solely for data. You may need to label them appropriately to avoid end-user confusion.

The example diagram below uses VLAN 100 for your current data network, and VLAN 200 as the new voice network. Instead of relying on the current data network infrastructure to handle an extra VLAN, a second physical network is added (but which also runs on a different VLAN).


The standard Frodo data access ports would connect to the data network on switch 1, and the FroDo Chorus port would connect to the voice network on switch 2.

Here, switch 1 and 2 would each present their respective network (VLAN 100 or 200) as an access port for the FroDo connection. Downstream, all ports would be presented as access ports, as only one VLAN is being carried (unless perhaps you're using a management VLAN on your switches). In this setup one network can only serve data and the other can only serve voice.


One of the Chorus requirements is an End-to-end QoS enabled network, this is to mitigate issues during busy times of day, or perhaps in the future, when large amounts of data traffic will affect the delivery of voice packets (as voice packets need to arrive in the correct order and in-time).

If you are using a separate physical network for your VoIP phones this is less of a priority, however if you are using a converged network, or passing through a shared core switch, then QoS is important.

The proposed QoS packet marking (DSCP Class Selectors) is as follows:

Traffic Type



Layer 2 COS

Drop Precedence

Voice Payload




Strict Priority











Network Control




Network Control

The ITSS must identify the device types in their network. In Chorus there can be three types of devices:

    Untrusted – usually a workstation where the user can interfere try to send traffic marked with increased priority.

    Trusted – A physical phone device that sets the priority for the voice and signalling packets itself.

    Conditionally trusted – where a single physical connection hosts both trusted and an untrusted device

When Unify phones are used, via the voice VLAN, the packets are already marked according to the scheme given above, hence the only thing that needs to be configured is the DSCP trust settings on the switch port.  You will also need to configure the queue for voice payload and network signalling as strict priority. You can plan the rest of the queues according to your needs.

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