|
 |
|
General Information
|
Add To My Personal Library |
May 23, 2008
• Vol.30 Issue 21
Page(s) 12 in print issue
|
VoIP Phones & Systems For The SME
Some Helpful Hints To Guide Your Purchasing Decisions
|
 VoIP phone and system purchases require many considerations. There are interoperability concerns; cost and management concerns; and network, usability, and quality considerations. Above all, an SME needs to know the depth and variety of options it needs to consider beforehand, so it won’t discover them after the purchase is already made.
 Look For SIP Support
SIP is the new standard for multimedia sessions such as VoIP. The way that SIP supports VoIP calls somewhat parallels how the SMTP supports email messages. Among SIP’s many duties, it “initiates” and manages Internet phone calls between callers, adds callers to existing calls, and terminates calls (or sessions). SIP manages sessions for multimedia phone and mobile device transmissions, such as instant messaging and video, too.
While there is still some H.323 standard hardware available for VoIP, most vendors are building their hardware based on the SIP standard, which is replacing H.323, according to Rich Costello, research director of enterprise communications applications at Gartner. To ensure that phones and systems will interoperate with each other and support future hardware and applications, an SME should look for the SIP standard in all VoIP products that it considers, according to Costello.
Consider The Benefits Of Hosted PBX
PBX systems enable SMEs to switch multiple phone lines in-house without paying the phone company for each individual line. SMEs must install, manage, and configure traditional PBX onsite, according to Andy Abramson, blogger at VoIP Watch and founder and CEO of Comunicano (www.comunicano.com). Then, there is hosted PBX.
With hosted PBX, according to Abramson, the Internet is an SME’s phone network. The SME doesn’t have to install it in-house, so it doesn’t require any additional physical space. The hosted PBX provider manages it for the SME, and the SME only pays for what it uses, so it is less expensive than traditional PBX. “Hosted PBX gives the IT manager more flexibility and capability,” Abramson concludes.
Think Unified Communications
Think of VoIP as part of a larger move toward UC (unified communications). “Even SMEs are breaking communications silos down to bring phone systems, email, messaging, and videoconferencing to a single, integrated platform,” says Costello. One can easily demonstrate the practical applications of a UC platform.
With UC, Costello illustrates, employees can click a Web link to bring a meeting that started in IM into a phone call. They can add data collaboration to a call. They can add videoconferencing.
Traversing NAT
NAT (Network Address Translation), which is necessary for local networks to communicate with global ones, can prevent VoIP phones from connecting, according to Abramson. A brief understanding of networks and NAT will clarify the issue here.
Network administrators use private IP addresses on local networks; private IPs are reserved for these kinds of networks. Because there are limited numbers of private addresses and there are many, many local networks, these addresses can’t be routed across the Internet. Otherwise, many places on the Internet would have the same IP address, making it impossible to route traffic to them.
NAT translates local IP addresses, which are not globally routable, to unique, globally recognized IP addresses on the Internet so traffic can reach the ’Net.
“Most VoIP phones can’t traverse Network Address Translation,” says Bart Kohnhorst, vice president and general manager of business communication systems at Samsung Telecommunications America (www.samsungtelecom.com). While an SME could use a VPN to enable a VoIP phone to traverse NAT, this isn’t very practical for remote IP phones that change locations frequently.
In this case, SMEs want to be aware that there is another option. Remote IP devices (VoIP phones) are available with native NAT traversal, according to Kohnhorst. So, the ability to cross NAT from anywhere goes wherever the phone goes. This enables VoIP phone mobility with security and saves the trouble and expense of setting up a VPN everywhere that people might want to make VoIP calls.
Know & Apply Codecs
Codecs are voice encoders that compress packets (pieces) of VoIP traffic much like digital sound encoders compress sound or music files to the MP3 or MP4 formats, according to Kohnhorst. Different voice codecs are useful for different situations, particularly differing constraints on bandwidth.
For example, the G.711 codec is a 64Kbps codec. “It is a larger packet with less compression that offers more voice quality,” says Kohnhorst. Where an SME has lots of bandwidth and wants the best voice quality, it should specify this codec.
Another codec, G.729A, compresses the voice packets a lot more but renders less voice quality. Where an SME needs a voice packet that can cross low-bandwidth networks and yet offers the best voice quality for that bandwidth, the company should specify this codec.
“A small business owner we know from Argentina goes back there one month every summer. Though the business networks there aren’t that reliable, he can connect to the home business network here in the U.S. using the G.729A codec,” says Kohnhorst.
SMEs want to work with vendors who know the difference between codecs and will allow them the option to specify one codec for high-bandwidth applications and the other for low-bandwidth applications.
If this brief list adds even one new variable to an SME’s VoIP purchase ponderings, then the company should investigate much further before it decides on a product. 
by David Geer
Most Important Considerations
SMEs should consider the following broadly applicable VoIP purchasing techniques in most scenarios.
• Make sure to have 100k in bandwidth free and available for every conversation when determining whether the enterprise really has enough bandwidth for VoIP, according to Andy Abramson, blogger at VoIP Watch and founder and CEO of Comunicano (www.comunicano.com). With this understanding, it’s easy to see that DSL or a cable modem line won’t cut it.
• Get VoIP phones that are both wired for Ethernet and wireless for Wi-Fi connectivity, notes Abramson. “That way, people can wander, and all internal calls within the building are free of charge because they stay on the network.”
• “Make sure the vendor is going to be around to support the purchase,” Abramson says. An older vendor with roots, commitments, and financial means is an obvious choice. A new vendor with strong management, skills, and reputation who proves out through considered research can also be a sharp choice. |
|
|
