The days of having separate, dedicated networks for video, voice, storage, and general data applications are behind us. In the past, many IT departments had separate groups to manage voice and data, with separate wiring and infrastructures. They even used different vocabularies.

Many companies have been tempted by the notion that everything should be managed in one big happy converged infrastructure, with everything running through the same switches and wires.

To read why that may not be such a great idea, see my story posted in ArsTechnica today.

More and more companies are migrating to SIP trunking services. In fact, one-third of 300 enterprises surveyed by Webtorials have deployed SIP trunking, with an average cost savings of 33 percent. In this ebook for Fierce Enterprise Communications, I wrote articles talking about how you want to take the next steps from your voice over IP telephony and does SIP trunking really mean the end of the public switched phone network.

You can register and download the ebook here (my work is on the last page).

Voice over Internet Protocol (VoIP) telephony has the wonderful potential for cutting communications costs and delivering additional features. But making the switch isn’t a slam-dunk, and you could have potential problems that could end up costing you more money and time in the short-term as you try to adapt your infrastructure technology to handle voice traffic over what is essentially a data network.

Here are five questions that you should answer in an article I wrote for CIOUpdate before deciding on the appropriate system for your enterprise.

Getting your company ready for a telephone switch migration is never easy, and made especially more difficult when you are trying to move towards Voice over Internet Protocols (VOIP).  Apparent Networks surveyed hundreds of network managers last June and found that more than 36 percent of them have delayed application deployments such as VOIP because of network performance concerns. Perhaps more of an issue is that 26 percent of respondents did not have the capability to validate their service level agreements. When asked which of their current applications stress their networks the most, VoIP was the most often cited by 73 percent of the respondents.

Here is a guide to help you through the transition, and a collection of five questions from others who have gone through the process that have found helpful.

Do you need to still support any analog phone lines? Before you switch over to VOIP, it pays to do a careful census and see where you might still require analog phone lines, such as to tie into a security system, a front door intercom, or a fax machine. Then find out how easy it is to mix and match these analog lines with your digital PBX, or what additional equipment will be needed to support these lines.

The city of Powell Wyoming was using an aging 3Com NBX PBX and looking to upgrade to VOIP, but there were worried about their connections to their 911 emergency response system, which made use of analog lines. “We were able to put an analog card in our new Altigen PBX and mix and match just fine,” said Zack Thorington, the IT specialist for the city. “We got the best of both worlds.”

Do you know what your WAN bandwidth usage is and what is running over it? Your VOIP system puts particular stress on wide-area links so it is important to understand the overall usage, particularly during peak times of day.  “We have a metropolitan fiber loop with ten megabits up and down to our offices here, so bandwidth wasn’t an issue,” said Duncan Hill, a partner at the incubator BaseCamp Partners in Toronto, Canada who uses the Jazinga VOIP small business system.

“The main challenge with VOIP is understanding Quality of Service (QoS) issues. My Jazinga system ensures that my voice traffic gets priority on my network so that my IP calls are successful. I didn’t have to do anything, the system just takes care of it,” says Bill DiNardo, the managing partner of Eventi Capital Partners, a Toronto-based venture capital firm. One of the reasons he chose the Jazinga product was because it automatically prioritizes the voice traffic on his network. “It shapes your traffic and manages your voice PBX, all in one small appliance. And the call quality is consistently better than all of the hosted VOIP solutions that we tried. It is easy enough to use that I can manage it myself, keeping the total cost of ownership low,” he says.

“Customers don’t realize how top-notch their networks need to be to handle VOIP,” says Daniel Song, senior services engineer with Indianapolis, Ind.-based Interactive Intelligence Inc. The company builds call center applications and other business communications solutions. “We were noticing that many of our customers were not yet ready for VOIP, so we needed a way to proactively address any potential voice quality issues before implementing our solutions.” The company purchased AppCritical from Apparent Networks to test their customers’ networks and to assess call quality before they deployed anything.

“AppCritical looks at the end-to-end network path to find problems, such as duplex mismatches, congestion, QoS alterations, and bandwidth limitations.  We are able to diagnose the behavior of the voice packets at each network hop and pinpoint where the problem is occurring. We are also able to verify QoS policies and make sure that service level agreements are being met.”

And while you are looking at your WAN bandwidth, don’t forget to examine your network switches too. “Most companies are going to need a good amount of bandwidth for their internal VOIP network, perhaps 100 Mbps throughout their buildings,” said Joseph Bennett, the IT Manager at PTR Baler, a Philadelphia-based industrial company who has been using Alteva VOIP products for about a year. “But we did need to upgrade our switches to support Power over Ethernet because we wanted to power all our phones from the wiring closets. Even with these upgrades, we are still saving somewhere around $2,000 or $3,000 a month on our phone bills, which works out to a nine-month return on the new system.”

Do you need any virtual LANs for voice, or some other way to segregate voice traffic? “We have one vLAN for VOIP internally we will be using it eventually on 70 phones now,” says Tomeu Vidal, the IT manager City of Campos, Spain, where they have deployed Entrasys switches. “Many of our customers are setting up segregated voice vLANs, or using QoS policies to ensure that voice packets have priority and won’t get dropped,” says Song. “Part of the problem is being able to understand what the peak call volumes are during the day and making sure you run your assessment during these times to see how many concurrent calls the network can handle while other types of traffic are present.”

Can you leverage a new office move or take advantage of a system coming off lease to do a wholesale upgrade? As these older PBXs age, they become less reliable and it can be a compelling time to do an upgrade. This is what McCune Brooks Hospital in Carthage, Mo. did with an aging Nortel PBX along with a move to a new hospital complex. “It wasn’t going to make much sense to relocate the Nortel, and we had to have a new system running in place before we made the move, so we went with Siemens,” says Wes Pool, a technician with the hospital.

The City of Powell Wyoming was experiencing a lot of downtime with its 3Com PBX – “sometimes we were down for 20 minutes or more. With our new Altigen PBX, I never have had to reboot the system unless I have made some specific upgrade over the past three years,” says Thorington.

Do you need particular features that your present phone system can’t easily meet or cost-effectively implement?  “We were stunned by the level of functionality and our phone bills are next to nothing here,” says Hill.  “At the end of the day, we wanted the features but weren’t willing to pay the traditional PBX and landline prices for those features that we get for a reasonable cost with our VOIP system.”

There are some VOIP features that are big productivity wins. “Our Jazinga VOIP solution has great features that most business owners wouldn’t know are possible or affordable. I am not sitting at my desk 9 to 5 everyday. My Jazinga system allows me to have an extension to the office system at home and other office locations that I work from, it even has the ability to simultaneously ring my desk and cell phone,” says DiNardo.

Robert Paglione is the CEO of Benefits Consultants Group Securities, Inc. of Riverton, N.J. “We were using a traditional Avaya/Lucent PBX and needed real-time call reporting and the ability to record our call center conversations. We needed to be able to reference a prior call in case of disputed transactions or instructions from our clients, as we do a lot of wealth management with high-net worth individuals. The Alteva system we purchased is better than what we were using, even though initially I had my doubts when I first starting looking at them because I didn’t have much experience with their product.” In the three years that they have been using the system, they never had an interruption in service, too. “We had a lot of downtime with the old system and a lot of finger-pointing as to whom was responsible. With Alteva, we have experienced about a 15% savings in our costs.”

“One of our favorite features with the new Siemens PBX is the ability to retrieve your voice mails from a trusted number without having to always key in your password, such as most of us do with our cell phones,” said Pool. “It makes it much easier to dial in for your messages when you are calling from the road, since you are taken right to your inbox.”

Part of the feature game is making sure you write detailed specifications in your request for proposal when the time comes to bring in vendors to bid for your business. “We wrote our specs to be very demanding, and included support for call parking and call waiting and having great auto attendant and management features,” said Thorington. “Once you experience a system that is lacking in these features, it becomes easier to figure out what you want in a more modern phone system.”