Basic Concepts

A complete VoIP broadcast phone system consists of several components.

One thing to keep in mind is that VXs is not a complete phone system in and of itself. It is a collection of SIP endpoints that have to be registered to a local or cloud PBX, a compatible hosted VoIP provider, or a gateway device.

This diagram shows a generic installation that could be used standalone with one studio and an analog audio console. Two Ethernet ports are used on the VXs engine to isolate the networks that are present in this example. Earlier versions of the Telos VX platform had two Ethernet ports designated LAN and WAN. With VXs, you have complete control over how your interfaces are assigned. In this example, eno1 is assigned to SIP and eno2 is assigned to AoIP traffic, though you can route SIP and AoIP over the same interface if desired.

These days, calls can arrive at your VXs system multiple different ways. Each delivery method has its own set of positives and negatives. If VoIP is relatively new to you, we recommend that you consult with our Telos ProService Field Application Engineers or one of our worldwide partners to help you find a solution that will work well for your application.

To illustrate the point that VoIP telephony involves more than one component, this diagram shows a very simple, 4 line phone system. Here, the connection to the outside world is ordinary POTS lines from a traditional phone company. They are fed into a device called an FXO gateway, which converts them to SIP channels that this 4 line VoIP phone can peer to on a one-to-one basis.

You could do the same with VXs in place of the VoIP phone to create a very simple broadcast phone system without a PBX. (In this example, that system would be limited to 4 lines, because the depicted POTS gateway only supports 4 lines.)

While it’s unlikely you would want to do this in 2023, as inexpensive, high quality VoIP options abound, it demonstrates the point we discussed above - unlike the POTS based broadcast phone systems of the past, VXs operates like a modern VoIP phone and requires something more than a simple handoff from the local phone company to function.

While this may sound complicated, it also gives us tremendous flexibility. After calls from the PSTN (Public Switched Telephone Network) are converted to IP, either by a VoIP provider, or a gateway like the one above, they can be routed anywhere in the world, just like any other IP traffic.

Quality VoIP providers leverage this technology to deliver superior service with innovative features at a fraction of the cost of most traditional phone companies.

Getting VoIP phone service

As of this writing, SIP is a mature technology and there are options at virtually every price point. It would be impossible to cover every potential provider’s capabilities, partly because they are constantly evolving.

That said, both Telos and our worldwide partners have deep experience in making VoIP work for broadcast. We can offer suggestions that will help you avoid challenges based on our experience with several different providers. Contact Telos or one of our worldwide partners for details.

Livewire+ is used for audio I/O and GPIO

Telos VXs accepts and generates many audio channels. Using Livewire+, it’s possible to make them all available through a single Ethernet interface, along with all GPIO commands and status indicators.

For facilities with Axia consoles or consoles that utilize AES67, this approach saves money and simplifies installation. When needed, analog and AES/EBU I/O can be provided via Telos Alliance xNodes.

Telos Alliance xNodes feature stereo I/O, but each stereo input or output can be configured for dual mono operation. For example, for a studio with two phone pots on a board, you can use a single L/R in and L/R out of an analog or AES/EBU xNode to drive both pots. (For AES, keep in mind that the L and R signals will enter and exit the xNode on a single cable pair for input and another single cable pair for output, so you will need some means of splitting then routing the audio post xNode.)

Make sure you account for a program on hold audio input for each studio when planning an xNode purchase.

Note: VXs is highly scalable and can generate many more channels of audio I/O than most Livewire devices. If you plan to run more than 43 channels of I/O (including program on hold and any channels used by Acoustic Echo Canceller) make sure you use a gigabit ethernet port on your Livewire switch.

Studios and Shows Defined

Telos VXs can support multiple studios and can share lines between studios.

A “studio” includes all the I/O resources needed to support operation for one physical studio. This includes AoIP inputs/outputs, program on hold audio, GPIO actions, GPIO indications, and the acoustic echo canceller.

A “show” is a profile that assigns extensions to line buttons. With VXs, you can assign any “show” to any “studio.” Within a show profile, you can also define whether a particular line button is on a selectable channel, or assigned to a fixed channel. You can also determine whether each line is blocked or not when the “block all” feature is engaged on a VSet, and assign custom ringers to each line.

Selectable and Fixed Lines

VXs supports what we call “selectable” and “fixed” lines. It’s possible to have a mix of each type in any studio.

If you’re in North America, you’ll most likely want to use “selectable” lines. Fixed lines are more common in European deployments. With fixed lines, a specific extension is always associated with a particular button on the VSet phone and a specific fader on the console. It’s as if each line has its own hybrid. This allows VIP numbers and hotlines to have fixed and dedicated console faders. Auto answer is also an option for fixed lines.

Multiple calls assigned to a single fader have individual hybrids and are actively conferenced within the VXs engine using an internal mix-minus. Calls assigned to different faders would normally be conferenced via a mix-minus of some kind within the mixing console.

Selectable lines use an operating style like most previous Telos phone systems, where there was a line selector before the hybrids, and any line could be assigned to any hybrid.

Most operators are used to these older systems, where you have column of buttons and pressing one takes a line and drops the previous caller. We have kept this operating style as the default for VXs. We have also kept the “lock” function that allows the operator to keep VIP callers on-air while answering and dropping additional calls.

Keep in mind that all faders (fixed or selectable) count against the number of channels you’ve licensed for VXs.