Gobs on Sticks

Thoughts mostly (but not always) about the voice-over business, from London Voiceover Artist, Mike Cooper

  • About the author

    My name is Mike Cooper. I'm a full time Voiceover Artist living and working in London, and this is my blog. Find out more about me on my main website (there's a link further down this column), or if you'd like to hear some of my work, check out the files below.
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ISDN – the Race to Replace (it)

Posted by MikeCooper on October 14, 2008

It’s been a week or so since I blogged about my dilemma over ISDN, so I thought it was time to share some more with the group as part of the recovery process.

As I was saying, ISDN, despite being a technology from the 1980s, remains the de facto standard for establishing point-to-point audio between voiceovers and producers. This is still the case both here in the UK and in the States, and ISDN’s ability to maintain a constant bitrate connection between two places is a major factor in this. There are two main reasons why the ADSL broadband internet which so many of us now have can’t match it. The first is that ADSL is optimised (or skewed, depending on your perspective) to favour downloads over uploads. That’s why it’s an “Asynchronous Digital Subscriber Line”, rather than a “synchronous” one, where the data flow would be the same each way. If you’re on a slowish ADSL line, where your quoted bandwidth is only 1 or 2 Mbps, then your “up” channel probably isn’t going to cope too well with you trying to stream audio to a third party. A trip to any of the online broadband speed testing applications will be enough to witness the way things are stacked in favour of downloads over uploads.

The second reason why ISDN wins the battle is that the internet is organised differently to a point-to-point connection. Internet Protocol (IP) is specifically designed to route “packets” of data via whatever route is necessary to get them to the other end. When you send an email or download a web page, it’s possible that the components that make it up have reached you via a variety of travel routes. The internet was originally a military installation, and was built around the idea of being able to cope with any one server being taken down unexpectedly.

When you’re reading your favourite website, the fact that it might take some of the bits a little longer to arrive than others isn’t so much of a problem. Even when you’re listening to music or watching TV over the internet, a certain amount of latency is acceptable, and the various playback methods constantly “buffer” enough data to try and cope. Most of the time it works pretty well for data coming in one direction, to you at your PC.

But with a voiceover session, we’re talking about two “quality” lines going in different directions. The studio at the far end needs to hear the voiceover, and they need to be able to talk back to the voiceover in real time, without delays or holdups due to buffering when one bit of the network starts to run slowly.

So, with all this in mind, I – like so many in the industry – have been paying very close attention to the search for the Holy Grail: ISDN performance over IP. At time of writing there are principally two computer programs which aim to replace the need for an ISDN line and allow you to use your broadband line in its place. They are called “Source Connect” and “AudioTX Communicator”.

“Source Connect” is a plugin which works with ProTools and with any program which supports VST or Audio Units. The idea is that, as long as both parties have the relevant software plugins and a reasonable speed connection, the voiceover appears as a channel on the application’s mixer, complete with talkback buttons and so on. Neat, eh?

“AudioTX”, on the other hand, doesn’t require any special software other than AudioTX at either end, so you can use it with whatever equipment and recording software you like. Again, it will do quality audio over IP with talkback. But it already holds a trump card in the nascent battle to replace ISDN. And that is that it can “do” ISDN connections too. As long as your PC has an ISDN card in it (and the only drawback here for me is that it does have to be a PC, rather than a Mac) then AudioTX will happily circumvent the need for a hardware ISDN codec. (For an encore it will doubtless calculate Pi to a million decimal places and make you a pot of tea to drink while you check the figures.)

If all this is getting a bit jargon-heavy, I apologise, but we’re kind of in that territory, whether we like it or not. A “hardware ISDN codec”, at its most basic, is a box with flashing lights that plugs into your ISDN line at one end, plugs into your mixer or soundcard at the other end and has a telephone keypad to let you dial people up for sessions. Sounds simple, but simplicity comes at a price, and that price is currently about £3,000 to £4,000 for something from Sonifex’s Prima range, which seem to be ones to go for.
So, someone like me seems to have three options at this point in time:

Option 1: Buy a hardware ISDN codec, at a cost of £3,500 or so (or pick one up secondhand).

Option 2: Obtain a copy of ProTools or similar and get “Source Connect”, the “pucker” version of which costs £1137 (cheaper versions are available without resilience for those internet dropouts). This allows you to do point-to-point sessions over IP, but only with those who are running Source Connect at the other end.

Option 3: Get AudioTX, which can do both ISDN sessions and those over IP. This would involve me buying a PC (grrr…) fitting it with an ISDN card (roughly £50) and installing AudioTX, which costs, wait for it… £550.

Hang on, that can’t be right, can it? The hardware box costs three grand and just does ISDN, which may be a dead duck within a few years, but the cheaper of the two software solutions can do exactly the same job over ISDN for now, as well as being able to waltz onto the IP dancefloor when the time is right. OK, buying a PC is a factor, but even so…

I think I’m beginning to reach a conclusion about all this, and I think you can probably see where I’m heading.



5 Responses to “ISDN – the Race to Replace (it)”

  1. R Freeman said

    There’s this too …


  2. mikecooper said

    Thanks, Rob. I didn’t know about that one! We live in interesting times…

  3. Hi Mike,

    Just came across your post re ISDN,as I’m searching on what the best solution for me is.

    I have a MAC and protools and not wanting to go down the PC route. There are now facilities that you can use with Virginmedia too. Source Connect is an option, but again the other end has to have it, although there are now bridging solutions.

    Just wandered if you knew of any places or people to get a secondhand codec ISDN machine from? Thought I would put it out there.

    I’m based in London too.

    I’ve been thinking about it for a long time now and need to bite the bullet, without putting a massive hole in my wallet!

    Any help would be greatly appreciated.

    • mikecooper said


      Thanks for taking the time to write.

      If I was looking for a second hand ISDN codec, the first place I’d check is eBay. You can even set up an alert so you get an email every time one comes up for auction. I’ve seen some real bargains, but also some scary prices. Personally, I wouldn’t be paying more than a few hundred pounds for ISDN at this stage, as my personal impression is that a change is in the air.

      I appreciate you say you don’t want to go down the PC route, but it’s always an option to buy cheap laptop and run AudioTX on that (it’s very modest in its requirements – just plug in a USB soundcard and a USB or PCMCIA ISDN card and you’re set). That might still work out cheaper than a Prima, but it’s certainly worth doing a Closed Listings search on eBay to see what they’re going for.

      Why do you need ISDN? Is it desire, or necessity?


  4. […] my old “Gobs on Sticks” blog, I wrote back on 14th October 2008 about the race to replace ISDN. It’s taken five-and-a-half years for that race to hit the starting blocks (and my sporting […]

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