In the first part of this series, we talked about the potential for Wi-Fi telephony in the enterprise and the prospects of Wi-Fi as a way to improve on-campus mobile telephone performance. Given the performance and cost of cellular telephony today, a growing number of Wi-Fi vendors are suggesting that enterprises might as well invest in a Wi-Fi network that can support both data and telephony applications. Wi-Fi telephony offers many positive benefits, and here we discuss some potential downsides of Wi-Fi telephony that every IT manager should know.
Wi-Fi telephony is a new technology that few would classify as "mature." In campus environments, there are various unknowns about how well the technology will perform and exactly how much capacity exists for telephony on the Wi-Fi network. Also, Wi-Fi uses unlicensed wireless spectrum, so there is little recourse for IT departments when the available frequencies become congested by workers or by neighbors whose signal is leaking over from next door.
The decision about technology maturity is one that each individual IT department must make on its own. There are many technologists who point to the fact that almost every technology has a "new" stage, and most of the time the industry is able to overcome challenges presented as technologies mature in enterprise environments. Others point to the underlying physics of wireless and the finite limits of the available spectrum.
At a broader level, IT departments must ask themselves the question of how much radiofrequency (RF) engineering they wish to tackle. Unlike data applications, telephony is intolerant of network dead spots, drop-offs and fade-outs. These lead to dropped calls and dissatisfied users.
If a third-party firm is used for RF engineering, IT managers should consider the fact that RF networks are living, breathing entities that change over time, so there is an ongoing need to measure, test and improve the networks over time. Wireless operators have teams of engineers doing this for their own networks, and a large enterprise should plan (both budget and process) to do the same at periodic intervals.
A key factor for users of Wi-Fi telephony is that the new call routing and IP telephony fall under the same user interface found on the existing mobile telephone. The transition between cellular and Wi-Fi telephony networks must be transparent to the end user, and the user interface must be the same one.
The reason for this requirement is that workers use their mobile telephones without thinking about cell sites and other carrier network functions – this is why mobile telephony is so successful. Efforts to lower call cost through enterprise dial-around numbers have been unsuccessful because they have complicated the user experience. These same requirements apply to Wi-Fi telephony, and IT managers should consider the user interface first and foremost.
More dual-mode handsets are on the market today than a year ago. The first generation of these devices offered reduced feature sets in order to accommodate the Wi-Fi radio, but features, capabilities and battery life are improving. One thing for IT departments to consider is the transition to Wi-Fi telephony, which will require re-provisioning users with dual-mode (cellular and Wi-Fi) handsets and educating new users about the (limited) handset options available to them. Also, Wi-Fi handsets must be certified for use on carrier networks, and some carriers have been slow to certify the dual-mode devices on their networks.
Wi-Fi hotspots Some IT managers have been told that their users will be able to utilize any Wi-Fi hotspot to make and receive telephone calls. This can be an important part of the business case for many IT departments. That said, many Wi-Fi telephones require a carrier, enterprise or free (no charge) Wi-Fi hotspot. When users have to enter account information onto a mobile device, the likelihood that it will be used drops rapidly.
In the worst case, users will find themselves unable to use a local Wi-Fi hotspot and will opt for the cellular network instead. Since the Wi-Fi telephony application should be transparent to the end user, many workers will find themselves unwittingly using the cellular network and paying the same price they pay now. This behavior is difficult to anticipate and predict, but it can work against an otherwise positive Wi-Fi telephony business case.
Dropped calls and support
Last, but not least, is the issue of dropped calls and support. When an on-campus user on the Wi-Fi network experiences a dropped call – this will happen – whom should he call? Is it an IT help desk? Or is it the carrier? If the Wi-Fi network is lost, and the call roams onto the cellular network, who takes that support call?
Without being too heavy-handed about this point, IT departments should anticipate additional help desk and support calls resulting from dropped calls on the Wi-Fi network. This will lead to additional trouble tickets and workload for the IT staff. These issues are to be expected and must be factored in as additional ongoing costs in the business case.
The bottom line for Wi-Fi
Every IT manager knows that there are no free lunches, and vendors that say that telephony can ride along "for free" on the Wi-Fi network are selling wooden nickels. There are some extremely positive reasons to adopt a corporate Wi-Fi telephony strategy, but a successful strategy will start with realistic expectations about actual usage and expected cost savings. These savings will then be compared with the additional cost of improving the Wi-Fi network to support telephony, making ongoing commitments to RF engineering, troubleshooting dead spots, increased help desk calls, trouble tickets and other associated operational commitments.
In the next two articles of this series, to be published in January 2007, we'll address an alternative to Wi-Fi telephony, which is to stay with cellular and integrate mobile telephony with the corporate PBX while improving in-building wireless performance for the public cellular networks.