Making the move to VoIP

Thinking of adopting VoIP? Ian Yates kicks off a week-long feature on what to watch our for along the way.

It no longer seems to matter which is more efficient or even which point solution will cost less, the future belongs to a single monster worldwide network based on IP and everything else will just be a branch line. Chances are if you're still using anything analogue you just won't be able to get connected within a few years. This is nowhere more likely than in the world of telephony. The question is no longer whether you should move to IP telephony and ditch the old analogue PBX. The question is why haven't you already done so?

Even if your corporate network isn't yet humming with VoIP bytes, no doubt most of your staff have got VoIP at home, and probably wonder why the money-saving technology isn't in the workplace. You've probably got some departments or individuals trying to use single-line VoIP adapters and wondering why they can't get them working thanks to your corporate firewall. In order to discover just how scary IP telephony can be and how much damage it can do to your network, SearchNetworking spoke with some of the industry's leading proponents to explore the risks of the move to VoIP.

Tony Warhurst from ShoreTel has some tips for network administrators. "My advice to the network administrators is to ensure that they have a highly reliable, highly secure network infrastructure already in place which most small to medium businesses do have in place already," says Warhurst. In simple terms, to then start running voice, well voice is really just another application that will run across that data network." Does that mean the existing network will cope? "In most cases, if they've got 10Mbps or 100Mbps switched to the desktop which most people are running nowadays, then their network will cope."

James Spencely from ISPhone suggests proceeding with caution. "If the business has a particularly good internal IT department, none of this should be a problem," says Spencely. "But for smaller offices, what you find is they often rely heavily on their IT partner or their consultant and that consultant may or may not have a lot of experience with a VoIP deployment or he might be using that as an excuse to learn himself."

Jules Rumsey from Telarus advises the implementation will be more dependent on Internet links than LAN issues. "It's very difficult in most cases to guarantee quality of service between the client and the server that's sitting somewhere in a data centre that is helping to coordinate their call and also the other end-point wherever that may happen to be on the internet," says Rumsey.

Pushkar Taneja from Global Connect points the finger at latency, rather than bandwidth, to ensure good quality VoIP. "A lot of businesses may have designed their IP infrastructure to cater for emails and web browsing," says Taneja. "If there is a delay in those type of environments I suppose you can live with it but when we're talking about the voice environment you can't afford to have "“ the term used is called latency. You can't afford to have a break in the communication. So it's important that any business that's looking at implementing voice over IP, they should get their network assessed first."

"It's about prioritising. It's ensuring that there is a segment available within the bandwidth to provide a clear path for the voice because what you don't want is the voice environment getting mixed up with the data environment," says Taneja. "So, typically when a system integrator comes around to do the assessment, they will look at what you have currently, where you need to get to, also of course having a look at how many users you will put in the environment so that they can provide you with an accurate piece of information on what your network should look like before you go and implement the technology."

Rumsey agrees that the quality of the link to the ISP is a critical factor. "If someone is in a SOHO style environment, they might have had quite a good experience with a basic ADSL connection," he says. "They may only make one call at any given point in time, so that might be quite appropriate for them. But certainly for larger offices when you start to have a number of concurrent calls then you start to really have a problem in terms of being able to manage the performance across the network and what we typically offer our customers is SHDSL as opposed to ADSL where we can offer a guaranteed bandwidth in both directions."

As well as bandwidth SHDSL provides the all important quality of service (QoS). "We manage the quality of service configuration for [customers] from the routers out at their end, through the network and out to the next site and, in fact, with those sorts of services we can offer up to 4 megabits per second symmetrically," says Jules Rumsey from Telarus. "That's quite a large number of calls that you can carry. Typically you would use a little bit over 100 kilobits per second for each uncompressed voice call. But then a lot of people, particularly if they're just using VoIP for inter-office, will use a compression algorithm but still you need, after overheads, probably around 32K per call in order to be comfortable."

Next: Can your existing kit cope?

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