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Feature Article
August 2003

Integrated Wireless VoIP Solutions For PBXs


In an earlier article, the basic concept of a wireless VoIP handset was described along with discussion of some of the challenges faced when bringing a quality product to the market. To develop such a product with a strong commercial value-add, it must be wrapped into a total �solution� and this typically means integration into a telephony system. Making calls between two wireless phones in the same network has limited value, but a wireless phone that has all the features of a desktop phone and can call Mom�now, that�s value!

By providing the same feature set as found on a desktop phone (e.g., transfer, conference, park, hold, etc�), a wireless handset becomes a real value-added business tool. Extending telephony connectivity to co-workers, customers, and suppliers through a wireless telephony integrated solution can offset the basic availability problem posed by the mobility of today�s office worker. Analysts estimate that some 65 percent of all phone calls end up in voice mail. This article will discuss the currently available options for providing a wireless VoIP solution, along with a peek into the future.

In general, providing an integrated in-building wireless telephony solution means coupling the wireless handset with a �gateway� that integrates into the on-premise PBX. It is through such gateway products that seamless access to the PBX can be provided. There are, however, a number of variant approaches to such solutions. Additionally, these options are expanding as the telephony industry itself embraces VoIP.

Businesses that adopt a wireless telephony solution will most likely require integration into their legacy PBX systems. Since a PBX is a rather large investment, it is typically not a consideration to install a new PBX just to add support for some additional wireless handsets�thus the �adjunct� solution approach. Basically, this product architecture approach provides a �gateway� solution that interconnects to the PBX and emulates either an analog or digital handset phone line. The gateway then acts as a proxy for the wireless handsets and connects them to the telephony network over an 802.11 wireless network through a defined call control protocol. This approach provides a way to preserve the PBX investment while supporting integration of a new wireless solution into the overall business telephony solution.

The gateway approach is predominant in the current market because major telephony vendors have not fully embraced VoIP as an integrated service provided by the PBX itself, while customer adoption of VoIP is advancing rapidly. There are a number of gateway solutions available on the market, but some consideration should be taken as to how they integrate into particular customer environments and the breadth of features supported.

Because the gateway is often a product of a third party (not the prime PBX vendor), integration is provided, but some limitations may exist with these solutions. If your company is investigating a wireless VoIP solution, it is important to understand the possible limitations and how they might impact your particular operation. Some of the limitations found with the currently available gateway products are:

Scalability -- Gateways are most often designed with a limited capacity for handset support. By estimating the number of active calls that need to be supported, one can judge the true capacity of any gateway solution. Of course, multiple gateway units can be configured onto a PBX, but limits in active capacity can impact the total cost and manageability of such a configuration.

Limited network capability -- Making a product/vendor selection should involve understanding the network feature requirements. Some solutions place restrictions on how they can be integrated into a multi-subnet network. Items such as remote management come to bear with this consideration. Enterprise customers will need to understand these criteria clearly.

Limited feature access -- Some cost effective gateway solutions provide only a limited feature set. Functions such as Caller ID, Voice mail message indication, and others may be important to an operation and need to be considered when making a gateway selection.

Now that we understand some of the considerations of a solution mix, it is also important to understand the basic PBX connection options.

Any of the �connection� methods mentioned in Table 1 can be suitable, but will depend on the specific requirements of the installation site. When evaluating a vendor�s solutions, be sure that a clear definition of telephony requirements is provided and reviewed. The good news is that there are reliable adjunct solutions available today that provide good voice quality and sufficient features to make it a true value add.

One dynamic that is clearly evident in today�s market is that of the telephony vendor�s eager support for VoIP solutions. Most market analysts predict that sales of VoIP PBX solutions will surpass the traditional TDM solutions some time in mid-decade (around 2006). What this means to the enterprise or commercial VoIP buyer is that additional solutions with higher levels of integration will be commercially available. It takes only a little literature search to find that all major telephony vendors currently offer either (1) hybrid VoIP systems, and/or (2) pure VoIP solutions as part of their product line. This market mega-trend results in one major impact on the resultant configurations: no gateway requirement.

The �native� VoIP support provided by these products affords solutions that:

� Reduce the number of vendors involved in the deployment;

� Incrementally lower the cost per handset (are more cost effective);

� Typically extend the functionality and reliability of the system; and

� Potentially support VoIP toll bypass capability.

As �native� VoIP solutions make their way into the marketplace, industry and enterprise businesses will begin a wholesale adoption of this technology simply because of its wide industry support and cost benefit over older TDM systems. When investigating a VoIP solution, it will be important to work with the telephony vendor and understand how their wireless VoIP offerings (if any) integrate into the whole solution being offered. As the technology finally matures into the market, the compelling ROI and lower total cost of ownership will make VoIP and wireless VoIP a success.

There are solid solutions in today�s market whereby a business may deploy a wireless VoIP product and leverage their existing PBX investment. Contacting the wireless VoIP phone manufacturers and learning about the connectivity options that they offer is the best method for understanding the �system� option. Integrating a wireless VoIP solution into a configuration that utilizes legacy PBX systems may involve interfacing with multiple vendors and the wireless phone vendor must be knowledgeable about these options. Learning the configuration options will be key in determining the proper final product configuration.

If your current telephony vendor offers a VoIP solution (VoIP desk sets and/or PDA software), they will most likely offer a compatible wireless VoIP solution. Whether your final solution is a hybrid-PBX or a full iPBX, it will be the telephony vendor that is most knowledgeable about any available wireless VoIP solutions.

The final word regarding planning the deployment of a wireless VoIP solution is that no matter what vendor(s) you purchase the components from, it remains very important that the underlying installed RF 802.11 infrastructure be certified for voice coverage and provides key voice prioritization features.

Richard Watson is director of telephony product marketing for Symbol Technologies� Wireless Systems Division in San Jose, CA. Prior to taking on the marketing role for Symbol�s NetVision family of WiFi Telephony products, he managed the software engineering team for three years and was responsible for developing Symbol�s WiFi Telephony products.

[ Return To The August 2003 Table Of Contents ]

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