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TechRepublic Resource Guide TechRepublic Resource Guide Document Transcript

  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) TechRepublic Resource Guide Voice over Internet Protocol (VoIP) Contents Mini glossary: Voice over IP (VoIP) terms you should know…………………………………….2 Learn about the terms, phrases and abbreviations that are essential to understanding the language of VoIP technologies, services and solutions. 10 ways to make your VoIP rollout easier……………………………………………………………7 Learn how to make the transition to VoIP a little easier by following these proven and easy-to- understand recommendations. Perform effective VoIP network capacity planning…………………………………………………9 Explore the techniques for VoIP network capacity measurement, planning and design. 10 things you should know about VoIP over wireless.............................................................13 Gain a better understanding of VoIP over wireless (wVoIP) for substantial savings on your telephone service. Sponsored by: Page 1 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) Mini glossary: Voice over Internet Protocol (VoIP) terms you should know Learn about the terms, phrases and abbreviations that are essentially to understanding the language of VoIP technologies, services and solutions. A M Asynchronous communications Mapping ATA Media Gateway Control Protocol C N Call processor North American Numbering Plan (NANP) Circuit switching Codec P Conference bridge Packet switching Packet D PoE Data compression POTS PSTN E Endpoint Q QoS F Full duplex S SCCP/Skinny H Simple Gateway Control Protocol (SGCP) H 323 Simplex Half duplex SIP High availability Soft switch Softkeys I Softphone IP PBX Synchronous communications IP phone IP telephony T IP TAPI IVR Telephony gateway J V Jitter Voice messaging VoIP session L VoIP Latency Page 2 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) Asynchronous communications Transmission method whereby bits are sent without synchronizing via a clock signal, but instead using start and stop bits to identity the beginning and ending of each block of data. ATA Analog Telephone Adapter; a device by which you can connect a regular analog phone (wired or cordless) to the Internet to make and receive VoIP calls. It converts the analog signal from the phone to digital and is available from VoIP providers such as Vonage or Lingo. Call processor VoIP providers' equipment that receives the phone number you dial, checks it for format validity, and maps it to an IP address. Circuit switching Older, less efficient but reliable technology used by the regular public switched telephone network (also see PSTN and POTS). A connection called a circuit is established for the duration of the call. Codec Coder-decoder software that converts audio signals into compressed digital signals so they can be transmitted across a digital network. It then converts them back to analog at the other end. Conference bridge A device for connecting several parties in a phone call so that all participants can hear one another. Data compression Methods of reducing the number of bits in a set of data so it can be transmitted more quickly over the network and then expanded to its original size when it reaches the destination. Endpoint A phone or computer associated with a phone number and temporarily or permanently assigned an IP address. Full duplex The ability of devices at both ends of a communications to send and receive information simultaneously. H 323 A set of protocol standards established by the International Telecommunications Unions (ITU) originally designed for video conferencing and also used for VoIP. Half duplex The ability to send data in two directions, but only one direction at a time. High availability Methods of ensuring rapid recovery from hardware or software failure employing redundancy and failover to backup components. Page 3 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) IP PBX Internet Protocol-based Private Branch Exchange internal telephone switching system that supports convergence of voice and data networks for routing calls within a building or organization. IP phone Looks like an ordinary phone but connects to an IP router with an RJ-45 Ethernet connector. These phones run software that allows them to handle VoIP calls without going through an ATA. IP telephony All telephone type services that work over TCP/IP, including VoIP, text messaging, and IP-based faxing. IP Internet Protocol; the network layer protocol by which computers on the Internet and other TCP/IP networks communicate with one another via unique binary addresses (32-bit addresses represented as “dotted quad” decimal addresses in IPv4 or 128-bit addresses represented as hexadecimal addresses in IPv6). IVR Interactive Voice Response; an application that allows users to access computerized information over the phone using keypad touchtones or voice commands. The commands are translated into digital queries and the results are returned from the computer hosting the information database. The results are then translated into computerized voice messages spoken to the caller. Jitter Variations in arrival time of data packets. Latency The amount of time it takes for a data packet to be transmitted from one endpoint to another. Mapping The process of determining to what IP address a VoIP call is to be routed, based on the phone number that is dialed. Media Gateway Control Protocol Protocol used to control telephony gateways. North American Numbering Plan (NANP) The system that the traditional phone networks use for routing calls based on the telephone number dialed. Packet switching Newer, more efficient technology used for IP communications on the Internet, by which data is broken into parts called packets. Different packets can take different routes to the destination, arriving out of order. They are reassembled into the original order at the destination. Packet A unit or “manageable chunk” of data into which complete messages are divided to be routed across the Internet or other TCP/IP network. Page 4 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) PoE Power over Ethernet; a method of sending electrical power over Ethernet cable to alleviate the requirement to plug equipment into an electrical outlet or other power source. POTS Plain old telephone network; a telephone industry colloquial nickname for PSTN. PSTN Public switched telephone network; the traditional circuit switching network used for transmitting voice conversations. Also see POTS. QoS Quality of Service; a guaranteed or predictable level of bandwidth, transmission speed, and freedom from dropped packets, delay, jitter, and error that is necessary to ensure adequate performance of particular applications. SCCP/Skinny Skinny Client Control Protocol; IP telephony protocol developed by Cisco whereby the telephone can communicate with an H.323 proxy. Simple Gateway Control Protocol (SGCP) Protocol used to control telephony gateways. Simplex The ability to send data in only one direction. SIP Session Initiation Protocol; a small and efficient application layer protocol specifically designed for VoIP communications. Soft switch Programmable switch that processes signaling for packet protocols and can be used to integrate telephone signaling with packet switching networks. Softkeys Buttons on a telephone handset or software keypad display that can be programmed by the user to activate a specific action, such as speed dialing a particular phone number. Softphone VoIP software that runs on your desktop, laptop or handheld computer and provides an onscreen telephone interface to allow you to make phone calls through your computer using its speakers or headset and microphone without a traditional telephone handset. Synchronous communications Transmission method whereby a fixed frequency synchronizing clock signal is used to synchronize data sent between a sending and receiving device. TAPI Telephony Application Programming Interface; programming interface for allowing Windows client applications to communicate with server-based voice communications services. Page 5 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) Telephony gateway The network device by which analog signals on telephone circuits are converted to digital data packets to enable calls between VoIP phone lines and standard PSTN phone lines. Voice messaging Application whereby voice messages are recorded, stored, and retrieved for later playback. A private access code is usually required for remote retrieval. Some systems can notify the recipient of the message via pager, outdialing, or e-mail. VoIP session A connection between two computers or VoIP phones using the same protocols and sending data across two channels, one for transmission of packets in each direction. VoIP Voice over Internet Protocol; technology for transmitting voice calls over a TCP/IP packet switching network such as the Internet, thereby avoiding long distance charges associated with the traditional public switched telephone network. Page 6 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) 10 ways to make your VoIP rollout easier Learn how to make the transition to VoIP a little easier by following these proven and easy-to- understand recommendations. You know Voice over IP (VoIP) can potentially save your company money, especially if your employees make many domestic long distance calls and/or international calls. It can also provide your users with convenience features, such as delivery of voice-mail messages their e-mail boxes. But making the switch can be a little scary. You depend on your telephone service and may not be able to do business without it, so it’s important to get it right. You can smooth the way to make the transition easier by following some or all of the following recommendations: 1. Assign responsibility The first step in planning for a VoIP deployment is to determine who will be responsible for each aspect. In some companies, the telephone system is managed by different personnel than the IT infrastructure. When you move to VoIP, the telephone system becomes part of the IT infrastructure. However, IT personnel may be unfamiliar with the special requirements of telephony applications. It is important to ensure that you have people on staff (either by hiring new employees or training existing ones) who understand the intricacies of VoIP. 2. Plan a multiple-stage rollout To avoid the risks involved in switching all your phones over to VoIP at the same time, you can first set up a pilot project for one department or group of users. This allows you to identify any unexpected problems while the impact is on a small scale, and you can find solutions before rolling out to the entire company. 3. Plan your security strategy Because VoIP calls are transmitted over the public Internet, the voice packets are subject to some of the same security threats as your data traffic. Unauthorized capture of packets to eavesdrop on conversations, man-in-the-middle and other call tampering, viruses, and IP-based Denial of Service (DoS) attacks that can bring down your VoIP network are all possibilities you need to guard against. Firewalls, encryption, and virus protection are just as important to protecting your VoIP transmissions as they are to protecting your data. Security should be built into your VoIP deployment from the beginning, not addressed as an afterthought. This whitepaper (http://www.voip-news.com/whitepaper/proactive-approach-voip-security/ ) outlines a proactive approach to VoIP security. 4. Consider quality of service Voice transmissions are less forgiving than other, non-realtime IP transmissions, such as e-mail. Latency, jitter, packet loss, and slow network performance can cause calls to be cut off or voice quality to degrade. Users are used to the high quality of the traditional telephone network (PSTN) and will expect the same from their VoIP service. Newer codecs can provide better tolerance to packet loss, but it’s important to ensure that your network has sufficient bandwidth and throughput speeds to handle VoIP properly. Remember that encryption and other security measures can slow network performance. 5. Evaluate and (if necessary) upgrade the network Many business networks "just grew that way" and have a conglomeration of components hooked together that may or may not support a realtime application such as VoIP. You should do a complete assessment of the network to ensure that all the cabling, switches, and other network components are of sufficient grade and speed. Infrastructure changes, such as creating separate VLANs for voice and data, need to be taken care of early. Page 7 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) 6. Consider future needs Plan ahead, both in terms of capacity growth and additional applications you may want to add in the future (such as video conferencing capabilities). If you are upgrading the network now to support an existing number of voice users, it may be more cost effective to go ahead and upgrade the infrastructure to a level that will allow you to address those future needs without tearing it all down and doing it over again. 7. Have a backup plan (for Internet connectivity) Unlike PSTN lines, your VoIP service is dependent on your Internet connection. No Internet connectivity means no telephone service. Redundant connections (which can also be aggregated to provide more bandwidth) will prevent loss of your phone service if one ISP should experience downtime. 8. Have another backup plan (for electrical power) Residential telephones continue to operate during a power failure because they operate on the electricity provided by the phone line. PBX systems generally require backup power systems, and your VoIP equipment will likewise need uninterruptible power supplies (UPS) and/or backup generators to power the VoIP server, switches, etc., in the event of a power outage. Another option is Power over Ethernet (PoE) switches, which can be used to power the IP phones. PoE allows access to both power and IP packet transmission over the same cable. You can find more information about PoE here (http://www.poweroverethernet.com/). 9. Consider cooling needs Rolling out hundreds or thousands of IP phones powered by PoE could put a heat overload on your wiring closets. Any time you greatly increase the number of electronic components, you have to deal with the generation of more heat, and PoE draws a lot of extra electricity. This may require the installation of extra cooling equipment. It also pays, when selecting equipment, to factor in the energy efficiency ratings of switches and other PoE gear. For more information, see Power and Cooling Considerations for Power-over-Ethernet (http://i.i.com.com/cnwk.1d/html/itp/APC_WP88.pdf). 10. Consider legal, compliance, and safety issues Remember that if you’re in a regulated industry (healthcare, finance, etc.), your VoIP network is subject to the same government compliance requirements as your data network, so it’s important to institute measures showing you are protecting the privacy of client data. Another issue is emergency services (E911). The portability of VoIP equipment complicates the ability for emergency operators to identity the physical location of VoIP callers. The FCC requires that interconnected VoIP providers supply 9-1-1 services to their customers, and providers are required to obtain your physical location so it can be associated with your number(s). If you change locations and take your VoIP equipment with you, make sure you update the physical location information. Of course, if power or the Internet connection is down, your VoIP service won’t work, so you should ensure that you have backup emergency phone service (landline or cellular/wireless) on site. Page 8 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) Perform effective VoIP network capacity planning Explore the key steps for VoIP network capacity planning and design. Network engineers, analysts and administrators characterize network capacity as the amount of traffic the network is designed to handle. When discussing voice over Internet Protocol (VoIP), network capacity becomes more a measure of how many simultaneous calls the network can process. This concept of "peak load", the maximum assumed volume that the network should be able to handle, will be the basis of your VoIP capacity planning. During your VoIP capacity planning process you should consider the following: • Your local area network (LAN) and/or wide area network (WAN) design • Existing data traffic on the network • The voice codecs your VoIP solution will use • Connectivity to the Public Switched Telephone Network (PSTN) • Your network's hardware infrastructure • VoIP and network redundancy The document will identify and explain the key steps in VoIP network capacity planning. Mapping the current network and gathering baseline network data Begin your VoIP capacity planning process by developing a clear picture of your existing network infrastructure. Identify each network link that will transmit voice traffic and document the link's bandwidth. This information will help you recognize and overcome potential bottlenecks. Without knowing your current network utilization, you can't accurately forecast how adding voice traffic will impact that utilization. Whether a bandwidth problem impacts your VoIP implementation or not depends largely on your existing network's layout. Network capacity is unlikely to block a VoIP deployment on a single-site network with high-speed infrastructure. Common networking problems, such as duplex settings and broadcast storms, will impact overall network bandwidth, but most modern LANs can easily pass a high number of VoIP calls. Bandwidth can be a roadblock when deploying VoIP over a WAN with multiple locations. WAN links are largely serial-based connections operating on T1 or fractional T1 lines. These are bandwidth bottlenecks on many networks and will impact VoIP communications. Once you accurately document your existing network's maximum capacity, you'll then need to determine the bandwidth you're network applications are currently using. A remote site connected via a 768Kbps leased line can easily support 10 VoIP phones, but if that link is oversubscribed, it many not be able to handle both voice and data traffic. For example, standard VoIP quality of service (QoS) guidelines specify that the network transmit voice traffic ahead of data traffic. This improves voice service, but can negatively impact other network applications. Large file transfers that once took five minutes, may take 20 minutes or more during heavy call periods. VoIP Capacity Planning Talking Points • Map your existing network infrastructure • Identify each network link's bandwidth and potential bottlenecks • Gather baseline network traffic data • WAN links can be VoIP traffic bottlenecks • VoIP QoS in a tight bandwidth environment can negatively impact data traffic • Measure capacity needs on average and peak usage data • Remote office usage may warrant increasing the speed of existing circuits or adding new circuits Page 9 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) • Simulate VoIP traffic to collect baseline VoIP data • Remote locations may need local PSTN gateways • Ensure the network hardware can handle the increase in traffic after VoIP deployment Using standard PRI or voice T1 lines, you will likely consume all available channels and be unable to place additional VoIP calls. Users will receive a fast-busy or an operator error. If enough bandwidth isn't available, heavy VoIP traffic can cause data circuit to constantly send data at their maximum bandwidth and eventually begin dropping packets. Even with QoS measures and compression in place, having more VoIP calls than the network can handle will also negatively impact call quality. Some vendors support admission controls that monitor bandwidth usage and generate an alert end users when traffic is too heavy to place a call. Needless to say, waiting for an ebb in network traffic is a poor user experience. To determine each connection's average and peak usage you can usually pull call records from your existing PBX and/or request historical call records from your telephone company. You average and peak usage data will help you determine how much PSTN connectivity you should retain and how much bandwidth you may need to add. With you network mapping and baseline data in hand, you should carefully consider increasing the speed of existing circuits or adding additional lines to remote locations. You should base this decision on each location's number of users and peak usage. As metropolitan-area network (MAN) technologies, like Metro Ethernet, proliferate, adding the higher bandwidth lines these services allow may cost less than adding more traditional circuits. Performing VoIP baselines Once you have a general VoIP traffic forecast, you can begin to test how the forecasted traffic will actually impact your network. Standard bandwidth monitoring techniques and protocol analyzers can provide good, basic information on much bandwidth you're using and help identify potential problems. You can perform a more detailed analysis using a variety of VoIP-specific tools. These monitoring tools will accurately replicate different types of voice traffic and watch for errors. They can monitor for VoIP problems such as jitter and delay. Jitter is the measurement of transit delay in voice packets and can be caused by many reasons. The end result is lower quality communications. You can select different VoIP codecs and simulate different call loads during real-time tests. Different codecs, such as G.711 and G.729, provide different sampling rates that affect packet size. Selecting a lower quality codec can dramatically affect the bandwidth usage on network links. During your test you should also test compression, which can increase available network resources and allow for more simultaneous phone calls. PSTN Connectivity During your VoIP capacity planning, you'll need to determine if remote locations will continue to have PSTN connectivity or if that connectivity will be consolidated at a central location. All phone calls would pass through WAN links to a central location where the calls would proceed out the associated PSTN gateway. Centralizing PSTN connectivity can simplify VoIP network planning and consolidating hardware can decrease costs and increase redundancy. PSTN consolidation can also impact VoIP network capacity. The remote location's size and bandwidth requirements will determine the impact's magnitude. When locations reach a specific end user number, your best option may be a local connection to the PSTN for local and offnet, long distance calls. For example, if your remote locations incur long distance charges to call each other or a home office, it might be better to pass internal voice traffic through your WAN but pass local, outside calls through a local PSTN gateway. You can easily accomplish this by routing calls based on destination area code. Again, your PBX records and telephone company history can help you determine how much call traffic falls into each category. Page 10 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) Hardware considerations Hardware directly influences network capacity. During your VoIP capacity planning process, you should carefully evaluate your existing hardware infrastructure and future hardware needs. Adding VoIP to your network may double overall traffic. You must ensure the network's core infrastructure and distribution-level points can handle the increase. You should establish 100Mbps, full duplex connections to every phone. Most modern Ethernet hardware can currently support this connection type. If your network hardware is modular and lets you easily increase port density, you will likely be able to use your existing equipment. If not, you may need to purchase new hardware. You must also guarantee that your uplinks to the network core can handle the additional traffic load. The PSTN gateway is another hardware consideration. Adding additional voice modules to you PSTN gateway may require an expensive chassis upgrade. Your hardware will also influence your network's capability for QoS, compression, and voice support. As these tools and techniques can increase network bandwidth, consider them as carefully as you would fat pipes and fast backbones. The ability to grow is key, and whenever possible VoIP should be rolled out in stages and capacity evaluated at each step. The bottom line Planning for VoIP capacity involves a number of different steps, from the bandwidth available on LAN and WAN links, to PSTN connectivity and hardware choices. VoIP, while not exactly “plug and play”, is a very feasible option given proper planning. WAN links will almost always be choke points and should be evaluated to make sure they can support the necessary voice traffic. Connections to the PSTN should be intelligently placed where they can be most beneficial. Finally, you should thoroughly examine the network hardware infrastructure to ensure support for both immediate and future VoIP capacity needs. Page 11 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) 10 things you should know about VoIP over wireless Gain a better understanding of VoIP over wireless (wVoIP) for substantial savings on your telephone service. Voice over IP (VoIP) can provide substantial savings on your telephone service by allowing you to use an IP network to make phone calls instead of the traditional telephone companies' public switched telephone network (PSTN). Many organizations today run IP networks over wireless technology, and it's possible to run VoIP applications over Wi-Fi, too. But you need to be aware of a number of issues when planning a VoIP over wireless (often called VoW, VoFi, or wVoIP) deployment. With the advent of WiMAX for longer range Wi-Fi communications, wireless phone companies (cellular carriers) are gearing up to offer hybrid phones that will use VoIP over Wi-Fi when a Wi-Fi network is available and switch to cellular when one is not. So VoIP over wireless encompasses different things, depending on the context. Here are some things you need to know about wVoIP. 1. Wireless VoIP offers advantages over cellular service A big advantage of wireless VoIP is that IP phones that work on Wi-Fi networks can be used in place of cell phones in many cases. Public 802.11 hotspots are often free or available at a low daily cost. If you're connecting to the Wi-Fi network anyway for Web and e-mail access, there's no additional cost to make VoIP calls other than the cost of your VoIP service, which is usually far less than the cost of cell phone service and may offer free unlimited international calling, something you don't get with most cellular plans. 2. VoIP over wireless LAN has many uses VoIP over a wireless LAN can provide easy internal calling for corporations, educational campuses, hospitals, hotels, government buildings, and multiple-tenant units such as dorms, with the ability to roam freely and advanced calling features such as voicemail and caller ID. Users can also use the LAN's Internet connection and an account with a VoIP provider to make calls outside the site, including domestic long distance and international calls, often at no extra charge. 3. WiMAX extends the reach of VoIP WiMAX is a long range microwave-based wireless technology based on the 802.16 standards. It can provide wireless broadband coverage to an entire metropolitan area or a large rural area, since WiMAX transmissions can span up to 75 kilometers (46 miles). With theoretical throughputs of up to 288 Mbps and practical throughput up to 70 Mbps, WiMAX has the bandwidth to support VoIP. 4. Voice transmission is more sensitive than data transmission VoIP is a real-time application, making it particularly sensitive to packet loss that can be caused in a wireless network by weak signals, range limitations, and interference from other devices that use the same frequency. To support VoIP, your wireless network must be reliable because users expect more dependability from their phone systems than from their computers. They expect a dial tone every time, no dropped calls, and high voice quality. 5. Mixing VoIP and data can degrade call quality Because of the sensitivity of VoIP applications to any disruption or delay, competing with data transmissions on the same wireless network can cause degradation of voice quality. It's important to implement quality of service (QoS) features to ensure that VoIP packets get priority. Page 12 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html
  • TechRepublic Resource Guide: Voice over Internet Protocol (VoIP) 6. Security is a bigger concern over wireless Security is already a major concern for VoIP, as sending telephone calls over a public IP network presents more security risks than using the proprietary "closed" networks of the telcos. Wireless adds another layer of security concerns, with transmissions going over the airwaves instead of cables and thus subject to easier interception. Common VoIP protocols such as SIP have their own security vulnerabilities. Any Wi-Fi network that will carry VoIP traffic must be secured, and such traffic should always be protected by authentication and encryption. On the other hand, many of today's telephone calls already travel over the airwaves, on cellular phones. 7. Older wireless LAN equipment isn't ready for VoIP If your plan is to roll out VoIP over your existing data Wi-Fi network, you may be in for a disappointment. For good performance, especially in the enterprise space, you need wireless LAN hardware and software specifically designed to work with voice traffic and address the prioritization and security issues. Look for integrated support for SIP and policy-based management that allows you to block unauthorized voice traffic. 8. Wireless VoIP equipment is available at consumer and enterprise levels Many popular vendors of consumer-level networking equipment (LinkSys, D-Link, Netgear) now make IP phones that work with their wireless routers. For example, D-Link's DPH-540 IP phone supports all SIP-based VoIP providers and works with 802.11b or g Wi-Fi networks. It supports WEP, WPA, and WPA2 encryption. At the same time, vendors of enterprise-level hardware, such as Cisco, are offering IP phones that work with IP PBX systems. For example, Cisco's Unified Wireless IP phone 7920 works with the Cisco Unified Communications Manager and supports EAP-FAST authentication for increased security. 9. VoIP over wireless smart phones can save companies money Today, many business people carry smart phones or handheld computer phones that run the Windows Mobile operating system, such as the Samsung i730 and Treo. These phones are provided by cell phone carriers, and using the telephone capability costs precious minutes. International calls call extra. However, by installing Skype for Mobile on these devices, users can make free or very low cost phone calls while bypassing the cellular plan and using the phone's Internet connection or in the case of Wi-Fi enabled devices, like the Samsung, using a wireless hotspot. 10. Future phones will combine cellular and Wi-Fi VoIP Industry pundits predict that the next generation of cell phones will all include built-in Wi-Fi. With these hybrid or dual-mode phones, you'll be able to seamlessly switch between cellular and VoIP over Wi-Fi when you come into range of a Wi-Fi hotspot, even within the same phone call. Landlines are expected to all but disappear as the hybrid phones become a single solution for telephony, operating off the user's Wi-Fi network at home and using cellular technology when there is no Wi-Fi network within range. This is predicted to lower the total cost of telephone service. Page 13 of 13 Copyright ©2008 CNET Networks, Inc. All rights reserved. For more downloads and a free TechRepublic membership, please visit http://techrepublic.com.com/2001-6240-0.html