Communication revolution: Why go VoIP?

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VoIP installation
As VoIP clearly involves computer and networking related technology, it is becoming a responsibility of in-house IT staff, rather than telecommunications technicians. As the majority of SIP phones and digital PBX appliances or IP phone controllers are Ethernet based, your existing IT staff can quite easily procure and install the necessary equipment and services.

Colin MacDougall of Mitel Networks suggests that small businesses do exactly that. “It’s not hard these days to engineer a network for Voice over IP, especially over a small LAN.” he noted. “Not all customers want to hand over the configuration of their network to a third party provider.”
Q&A   VoIP
Why is the audio garbled and dropping out?
Controlling VoIP performance can be occasionally difficult with consumer or SOHO level equipment. Unless you control the entire data connection from end-to-end, features like Quality of Service (QoS) (which are supposed to improve VoIP performance) can have potentially no impact whatsoever. Serious “carrier-grade” QoS requires an unfettered control over both ends of the network and ideally, the trunking in between. Other issues such as contention ratio, an Internet Service Provider issue which basically comes down to “broadband connections per DSLAM”, which is a kind of ADSL ‘switchbox’. Well-prepared ISPs will have better planning and greater investment in their architecture, allowing fewer users per DSLAM. This creates an excellent contention ratio. Discount price ISPs have far less investments in their infrastructure and are almost guaranteed to provide a terrible contention ratio, where you share the DSLAM with far too many users, causing a generally poor quality Internet experience. Contention ratios are a major point of difference between budget and premium ISPs - as traffic through the DSLAM increases, more signals will collide with each other and you will notice that your Internet performance, especially for time-sensitive applications like VoIP, suffers.

However, Colin has some words of warning to people using VoIP on consumer broadband. “If you’re pushing voice over ADSL, customers need to be realistic.” he said. “ADSL from different service providers has different contention rates, it generally has no Quality of Service (QoS).”

Additionally, some training in PBX or VoIP switch configuration may be required. “One of the issues with VoIP on a LAN or especially a WAN is engineering of the switches on the network. If they’re not properly configured, this leads to some of the horror stories you hear about Voice over IP.”


Choosing a VoIP service provider
Colin also maintains that problem solving issues with IP telephony are simpler when a single provider has set up and installed hardware and services. Not all services are equal, and some of the points of difference can be critical.

“Ask questions of that provider. Do they provide 802.1 P & Q, do they support VLANs, do they support Quality of Service?” Colin asks.

In some cases you can obtain various performance guarantees from your provider, before work begins. Colin explains: “One thing we do is provide a statement of works. This is a customer-supplier agreement. It’s a list of items that says: these are my responsibilities, these are your responsibilities, and if we both fulfil those, this is what the outcome should be. For small sites, the statement of works can be a very small, simple document. Some resellers put a small statement of works into their contract, some don’t.”

There are some benefits of having your provider roll out your infrastructure, as Colin notes: “Getting the provider to do it means that at some point down the track, there won’t be any finger-pointing. The customer then has that single point of contact, the advantage of ‘one throat to choke’. You have someone that is capable of owning that network right from the PBX down to the handset.”
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