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Voice over WLANs: Markets that benefit from VoWLAN solutions

Jim Geier's book Deploying Voice over Wireless LANs gives examples of how several different vertical markets benefit from wireless LAN voice networks.

Jim Geier's book Deploying Voice over Wireless LANs discusses the products and services needed for a wireless LAN voice network in your enterprise and necessary applications. VoWLANs have already been implemented into a number of enterprises in a range of markets, each of which benefits from both the general and more specific advantages of wireless voice.


  • Healthcare
    Hospitals were one of the first users of VoWLAN solutions mainly because of the significant need for effective communication among high-valued medical staff. VoWLAN systems allow hospital staff to not waste time looking for a phone to use.
  • Enterprises
    Enterprises are taking advantage of VoWLAN applications to provide mobility to workers and reduce costs through a common network infrastructure for voice and data.
  • Universities
    The use of VoWLANs at a university offers tremendous benefits by enabling university staff to stay in touch from anywhere on campus.
  • Retail
    To satisfy the needs of customers and staff, retail store managers must be accessible from anywhere within the store. Voice communications with these managers is crucial in providing customer satisfaction.
  • Warehouses
    Warehouses involve a host of functions where VoWLAN systems can provide significant benefits.
  • Manufacturing
    A VoWLAN system makes communications in manufacturing extremely beneficial because managers are constantly on the move.
  • Small offices and homes
    Many small offices and homes are installing wireless LANs to support mobile access to common Internet applications.
  • Security systems
    VoWLANs provide the ability for people to quickly report wrongdoings and suspicious activities in a variety of environments.


Hospitals were one of the first users of VoWLAN solutions, such as Vocera, mainly because of the significant need for effective communication among high-valued medical staff. The ability for doctors and nurses to respond quickly with verbal instructions is crucial for saving the lives of patients. For example, Children's Hospital in Madera, California, uses a VoWLAN system to support push-to-talk features on its VoWLAN phones to broadcast Code Blue alerts that summon emergency teams. Patients receive a higher level of care, which leads to faster recovery. VoWLAN systems allow hospital staff to not waste time looking for a phone to use.

An issue with deploying VoWLANs in hospitals, though, is the difficulty in providing adequate wireless LAN coverage. Hospitals include x-ray rooms surrounded by lead, irregular metal objects, and unpredictable traffic flows of people. These factors lead to significant signal impairments. In addition, RF interference from other wireless systems operating in the 2.4GHz band, such as frequency-hopping spread spectrum devices, can cause degradation in performance. As a result, installers must conduct thorough RF site surveys when identifying optimum placement of wireless access points.

Hospital in Northeast U.S. Benefits from VoWLAN Solution
Doctors and nurses at this hospital, as in others, are always on the move, taking care of patients. To do this effectively, the doctors and nurses must be capable of contacting each other immediately as emergencies arise, which is fairly often. For example, a nurse may find that a particular patient develops complications a few hours after surgery and needs immediate attention from a doctor. Before VoWLAN systems, the nurse would try calling the doctor on a cell phone. Cell coverage in the hospital was not very good, and the call would go immediately to the physician's voice mail. If the nurse could not make immediate contact with the doctor over the cell phone, which was about 75 percent of the time, the nurse would then call the doctor's pager. Pager coverage was very good throughout the hospital. The physician would receive the page and then find a wired phone to call the nurse. This task added significant delays because a phone could not always be found quickly, and the nurse would have to wait around a phone for the doctor to call (taking the nurse away from the patients needing assistance).

The hospital deployed a wireless LAN that supports the use of VoWLAN phones, enabling doctors and nurses to stay in immediate contact with each other. Now when a nurse needs a doctor's attention to help an ailing patient, the nurse can simply call the doctor directly using the VoWLAN phone. All calls go through because the wireless LAN was installed in a manner that provides signal coverage in all parts of the hospital. This solution significantly reduces communications delays, and patients receive immediate attention and care.

The hospital installed 120 wireless LAN access points to provide signal coverage for the VoWLAN phones. To determine optimum access point installation locations, the hospital conducted an RF site survey. Ensuring high enough signal strength and cell overlap throughout the hospital is very important to maintain effective operation of the phones and roaming.


Enterprises are taking advantage of VoWLAN applications to provide mobility to workers and reduce costs through a common network infrastructure for voice and data. In many cases, enterprises implementing VoWLAN are doing so as an extension to wired VoIP systems. A company, for example, can equip the majority of the employees with a wired VoIP desk phone, and VoWLAN handsets are given to the employees needing mobility. Certainly the benefit of going wireless is that users can carry their phone with them throughout the facility, which enables them to respond faster to customer needs and functions within the company. The use of VoWLAN phones also eliminates the costs associated with rewiring telephone lines when employees change offices.

Enterprise executives making the decision to spend money on the necessary hardware and services need solid numbers before committing funds. An issue with deploying VoIP, and especially VoWLAN, in enterprises, however, is accurately predicting ROI. Assessing the returns a company will achieve by enabling faster response to customer needs, for example, is difficult. A company must be capable of achieving significant productivity benefits before moving forward with a VoWLAN deployment.

Executive Management Team at Corporate Headquarters Benefits from VoWLAN Solution
A particular enterprise, as with most other companies, has an executive management team located in a centralized location of the company's headquarters facility. All of these executives are infrequently in their offices—they manage by walking around and keeping tabs on their various departments. For example, the IT manager is generally visiting with technicians distributed in various parts of the facility, making sure that projects, such as PC hardware upgrades, are going smoothly. The problem is that when issues arise, the technicians have no way of contacting the IT manager immediately. The technicians use a phone in the office where they are working to call the manager's office, and 90 percent of the time must leave a voice message. In most cases, hours would pass before the manager would receive the message.

The solution to this problem was for this company to make use of an existing wireless LAN and deploy VoWLAN phones to the managers. This solution enables just about anyone to reach an appropriate manager within seconds, without experiencing the delays of voice mail.


A university environment is highly mobile, with teaching staff and students moving among different classrooms, libraries, and offices. The use of VoWLANs at a university offers tremendous benefits by enabling university staff to stay in touch from anywhere on campus. This capability makes teachers more accessible to students, and the learning environment is much safer. A teacher, for example, can report safety issues as they occur, rather than having to wait until a class ends.

A challenge of deploying a VoWLAN system at a university is that coverage must include a wide variety of buildings and outdoor areas. An extensive RF site survey is very important to take into account the varying facility construction and obstacles blocking radio waves. Even after installing the system, reevaluating coverage from time to time is generally necessary to determine whether student traffic and campus functions offer major signal attenuation.


To satisfy the needs of customers and staff, retail store managers must be accessible from anywhere within the store. Voice communications with these managers is crucial in providing customer satisfaction. For example, a customer may need to replace a part found broken when putting together a newly purchased bicycle, or someone may need to know the status of a shipment of a particular brand of dog food. Whenever the need arises, immediate communication with the store manager is necessary, and customers cannot be kept waiting, or they will shop somewhere else. In this type of environment, VoWLAN really shines. In many cases, the retail store already has an existing wireless LAN, and the store managers and staff can benefit from low-cost telephony.

Retail stores use existing wireless LANs to support bar code applications, such as price marking and inventory management. These applications make the deployment of VoWLAN systems in retail stores more of a plug-and-play situation. The existing wireless applications, however, generally have very low capacity requirements, and the access points already in place may not be capable of supporting the much higher bandwidth demands of voice communications. For example, a store may only have a wireless LAN based on the initial 802.11 standard, such as direct sequence spread spectrum supporting up to 2Mbps data rates. This particular store would need to upgrade its access point hardware to at least 802.11b, which introduces costs for hardware and services in addition to purchasing the wireless handsets.

Retail Chain Goes with VoWLAN Solution
An electronics retailer with 230 stores throughout the United States sells PCs, software, and games. This company makes lots of calls between stores. A customer may want an item, for example, that a particular store does not have in stock. The store clerk would then begin calling other stores to check on the item's availability. This situation happens a lot throughout the day and results in extremely high telephone bills. Another issue is that the store clerk generally learns that the item is not in stock when he or she is with the customer where the item is supposed to be within the store. The time needed to walk back to the register area or office to place the calls to other stores adds enough delay that some customers decide to forego checking on the item at other stores. This delay results in losing potential sales.

To resolve these problems, the retail company decided to make use of the wireless LANs already existing in the stores and supporting bar code applications to support the VoWLAN phones. Now the store clerk can place calls immediately to other stores when performing inventory checks. This solution keeps the customer's attention and results in greater sales. The telephone bills are also much less due to being able to route the phone calls over the company's WAN infrastructure, which interconnects all the stores.


Warehouses involve a host of functions where VoWLAN systems can provide significant benefits. Clerks end up being scattered throughout the warehouse facility, which can be quite expansive, and communication with other clerks and managers is essential to perform various functions. In most cases, having the clerks and managers meet face-to-face to communicate is not practical. In fact, being able to even find each other is often not possible, due to the numerous rows of bins and products. For example, an order may come in for the shipment of a particular item to a customer. Rather than waiting for a clerk to return to the main office, having the shipping department call a clerk directly and have him pick the item is much faster and more productive.

As with retail environments, many warehouses already have existing wireless LANs. However, because these wireless networks primarily support relatively low-performance bar code solutions for implementing inventory management functions, the wireless LAN may not have enough capacity to support a large number of VoWLAN phones. A company must analyze the wireless LAN and ensure that adequate data rates, signal strength, and roaming exist to support wireless voice applications.

Warehouse Deploys VoWLAN Phones to Speed Up Operations
A relatively large warehouse was experiencing delays when processing orders. For example, when assembling an order for shipping, warehouse clerks would pick items from shelves based on lists prepared earlier in the day. Orders would often change, though, which would require the clerks to not pick certain items or pick others that were not on the list. To communicate this information, the warehouse manager would page the applicable clerk through an overhead loudspeaker system. The clerk would then walk all the way back to the manager's office to learn of the changes to a particular order. This process would incorporate delays, which significantly decreased the warehouse's productivity and order placement time.

The solution was to install a wireless LAN for supporting VoWLAN phones. As changes to orders take place now, the warehouse manager can call the clerk directly on the VoWLAN phone and explain the change to the order. This call avoids the need for the clerk to walk back to the manager's office, which speeds up the picking operation. In addition, the installation of the wireless LAN also makes setting up a wireless bar code system for performing inventory management functions possible. This solution will also save the company a tremendous amount of time and money when performing inventories.


In manufacturing facilities, line supervisors monitor production lines, and managers must be able to contact each other and other employees immediately to check the status of various operations and solve problems that regularly arise. A division manager in charge of a particular business unit, for example, is certainly anxious to ensure that the plant is getting products ready to ship in time to make revenue numbers. If a part of the orders for that period is at risk of not being completed in time, fixes can be considered and put in place to keep manufacturing on schedule.

A VoWLAN system makes communications in manufacturing extremely beneficial because managers are constantly on the move. In many cases, a manufacturing plant will have an existing wireless LAN in place, making the deployment of a VoWLAN extremely feasible. Even if the installation of wireless access points is necessary, the VoWLAN solution is still worthwhile because of the monetary benefits associated with immediate communications. In this situation, the value of the company to shareholders depends on effective communication among stakeholders in the manufacturing process. A VoWLAN solution allows managers to communicate immediately and solve problems to keep production in line with sales.

Toy Manufacturer Benefits from a VoWLAN System
The managers at a toy manufacturer were having trouble communicating with each other. For example, the manufacturing line for a particular toy would begin having mechanical troubles, which would require the manufacturing line supervisor to shut down production until someone could perform necessary repairs. This plant is large, and a single centralized maintenance group takes care of many production lines. The line supervisor would use his office phone to call the maintenance chief, who would then need to track down the right mechanic to fix the problem. The issue was that "phone tag" would result, causing significant delays. Often an hour or more would elapse before this coordination would be done and a mechanic would be notified that he needed to work on the problem. Meanwhile, the company would be losing $500,000 each hour the production line was shut down. Something had to be done to speed up communications needed to coordinate maintenance when problems arise on one of the production lines.

To solve the problem, this company installed a wireless LAN throughout the manufacturing plant to support the use of VoWLAN phones. All managers, supervisors, and maintenance staff were equipped with VoWLAN phones. A production line supervisor can now call the maintenance chief directly via VoWLAN phones. The maintenance chief may be out of his office assisting one of the mechanics and still be able to receive the call immediately. The maintenance chief can use the VoWLAN phone to coordinate the right mechanic to fix the problem. Because everyone carries the VoWLAN phone with them at all times, telephone tag is no longer an issue, and communication is immediate. This time savings significantly reduces downtime of the production lines, which in turn improves the company's profits.

Small offices and homes

Many small offices and homes are installing wireless LANs to support mobile access to common Internet applications. Service providers, such as Vonage, are strongly advertising the capability of using the Internet for making phone calls to augment or replace standard PSTN telephones. Home and small-office owners are taking advantage of Internet telephony to save money on long-distance phone calls.

The use of VoWLAN is further extending the benefits of VoIP by providing mobility and even replacing the need for a cellular phone. A consumer is likely to select a VoWLAN solution as compared to wired VoIP service to enable mobility similar to what cordless phones offer. Someone can take the phone around the house and talk while doing house chores.

A single access point can easily support most home and small-office voice applications. Range is sufficient for the entire home, and a single 802.11b or 802.11g access point can support the limited number of phones (generally only one) that will be in use simultaneously. RF interference from microwave ovens and neighboring wireless LANs set to the same channel can cause significant impacts on performance, however. Consumers may have to reconfigure the RF channel of their access point to have effective wireless voice service.

Unfamiliarity with wireless technologies may preclude some consumers from purchasing VoWLAN equipment. In addition, the inability of Internet telephony to operate during power outages and limited operation of 911 services may keep some consumers from moving forward with a wired or wireless VoIP solution. Despite these issues, though, VoWLANs in homes and small offices is expected to proliferate over the next few years.

Home Owner Finds Value in Internet Telephony
Madison Leigh of Fairborn, Ohio, found that her monthly long-distance phone bill was running more than $100 per month because she was making regular phone calls to her father, living in a rest home in Chicago. Madison was paying only 10 cents per minute, but the phone calls were running into the hours, discussing issues that her father was having living in the rest home. Madison saw an advertisement on television for Vonage Internet-based calling, so she investigated the service and found that it would save her approximately $70 per month. After hearing about Wi-Fi, she found that she could have wireless voice over Internet connectivity, which she thought was a good idea because she could talk on the phone from anywhere in the house, similar to what her cordless phone had been providing.

Jack's Foreign Auto Parts and Repair
Jack's Foreign Auto Parts and Repair, based in the eastern United States, is a small business specializing in the repair of foreign automobiles and the sale of hard-to-find automobile parts to car enthusiasts worldwide. Jack employs eight mechanics and one administrative person, who takes care of invoicing and paying the bills. Jack supervises the mechanics and provides necessary guidance on the shop floor. He is on the phone most of the day, making international calls, trying to locate rare parts worldwide for fixing the cars. His phone bill had been running nearly $1,000 per month! When purchasing a new fax machine at a local office supply store, he saw a Wi-Fi phone and router advertising the ability to slash long-distance phone call costs, especially overseas. After thinking about it a bit and doing some research on the Internet, Jack purchased the solution and installed it at his company. He now pays roughly $50 per month in phone bills.

Security systems

The ability for people to quickly report wrongdoings and suspicious activities is vitally important for providing security in all companies and organizations. A person equipped with a wireless phone, for example, can get critical information to the appropriate organization for it to respond to an emergency situation. For example, a security person in an airport can report the findings on an unattended piece of luggage, which would trigger a reaction from the airport security team. VoWLAN systems can certainly support these types of functions to bolster security through faster response to situations.

Companies can also deploy wireless security cameras that send video over wireless LANs. This approach is much more feasible than running wires to each camera. The ease of installation allows a greater number of cameras to be put in place, which increases the viewing of the different parts of a facility or campus.

A major issue with using wireless LANs for supporting wireless voice and video is that they are vulnerable to denial of service (DoS) attacks. A person wanting to disrupt the security system can block the flow of voice and video signals by jamming the network. For example, someone can transmit either an overriding RF signal or specialized protocols (such as multiple CTS frames having long NAV values) that block phones and cameras from accessing the network. Also, wireless video cameras are vulnerable to sniffing. For example, someone could passively monitor the video stream using a tool such as driftnet. Companies must consider these threats and plan accordingly.

Airport Improves Security with VoWLAN
Security personnel at a large airport in the southern United States continually walk throughout the airport looking for potential security issues and responding to passengers needing medical assistance. In the past, the security people would use two-way radios to communicate with a central security office, which would dispatch appropriate support staff in response to situations. The radios, however, were not reliable because of range issues. In some parts of the airport, the security agents would be too far away from the office to work effectively. In some cases, the range was so great that communications were not possible. In addition, the two-way radios were limiting, because only someone else having a two-way radio was able to communicate with the roving security personnel. Having someone use a phone to contact the mobile person was not possible.

Because of the need for improved security, the airport decided to take advantage of VoWLAN technology. A wireless LAN had to be put in place, but the airport had wanted to do so anyway to offer a public wireless LAN to passengers and other airport applications. It was much more cost-effective to build a common wireless LAN infrastructure for multiple applications. The public wireless LAN users could be kept separate from the airport applications, such as the VoWLAN solution for the security personnel, through the use of different VLANs. Now, security personnel can immediately report incidents that need attention and receive a quicker response than before.

Metro Rail Monitor Tracks with VoWLAN
A city in the midwestern United States has a passenger rail system that moves people around various parts of the city. Before implementing a wireless, video-based monitoring system, the operator of the train had to keep an eye on track conditions and report findings to maintenance staff via an unreliable two-way radio, which often fell out of range from the maintenance office, or through a cell phone. Both ways, however, took a great deal of time. The operator was finding that performing other important tasks was difficult, such as driving the train and being alert to the safety of passengers.

The city equipped the train with Wi-Fi cameras on the front of each train and mounted access points periodically along the tracks. A maintenance person can now view the entire track as the train moves—saving the time of the operator and a maintenance person riding on the train. Problems with the track can now be found and repaired much faster, saving time of staff, and making the transport system safer for passengers.

Return to the Main Table of Contents on the introduction page to read about the history of VoWLANs and determining an ROI.

Excerpted from Deploying Voice over Wireless LANs by Jim Geier. ISBN: 1-58705-231-8.
Copyright © Pearson Education. All rights reserved.


This was last published in January 2008

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