Strategies for successful IP telephony implementations

The significance of "legacy" is obvious to most of us, but perhaps not clear in the IP telephony sense of the word. A quick search reveals a better explanation pertaining to the context of the situation: a computer, system or software that was created for specific purposes but is now outdated; and anything left over from a previous version of the hardware or software.

In the ever-evolving world of technology for whatever reason, telecommunications departments have tended to have longer product lifecycles and more dissimilar environments than any application or IT unit in a company.

There are several reasons for this. It may have something to do with the heritage of limited innovation, exorbitant prices for contemporary technology or lofty maintenance costs.

So, it comes as no surprise that IP telephony remains a potentially perplexing technology for many companies, possibly tempering enthusiasm for wholesale employment of IP telephony products.

Indeed, a compilation of four leading analyst reports indicates that 2005 will be the year of "inflection" - when the rate of market growth changes. It is predicted that more IP lines will be purchased than digital, signalling the market`s preference for IP technology.

In light of this anticipated surge in market demand, a re-evaluation of a company`s IP telephony strategy is appropriate since the technology risk and company risk-tolerance have changed.

Companies should, therefore, understand the tradeoffs of each of the following IP telephony deployment options:

1. Hybrid
2. Greenfield
3. Forklift
4. Overlay
5. A combination of strategies

This strategy involves two components - an IP phone and an IP adjunct card that provides access to the PBX switch fabric. With the hybrid strategy, users get telephony service on an IP phone, but not much else. Similar to the sizes of PBX line cards that control access concentration and manage call blocking, these IP cards can only support a limited number of IP phones. If too many calls access the switch fabric or the card bus, contention may occur and cause users to hear fast busy tones, affecting service availability.

Furthermore, most vendors offer messaging services separately for users directly over IP, reducing interoperability with the legacy PBX. Audio quality is also limited to 8kHz sampling and 64KBPS maximum bandwidth.

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"Greenfield" takes its name from the "field of grass" that theoretically existed before construction began. The strategy involves the deployment of a new system in a new facility, often a new building on a campus, an office relocation, etc.

The opportunity is to create an experimental "island" of the technology to:

* Assess benefits
* Functional interoperability
* Cost control
* User acceptance

When the digital PBX infrastructures are complex and large, making wholesale change expensive disruptive and difficult, companies typically adopt the greenfield strategy. It is a popular choice when much of the gear is not completely depreciated or when the management team is sceptical of the benefits.

Here the implementation involves a complete removal of legacy equipment, hence the "forklift" analogy. Since most PBXs are large boxes that require power assistance to relocate them, many vendors consider this as a sales opportunity. The risk of failure can be higher than with other strategies.

The forklift often implies a flash-cut of the service, one day the old and the next day the new service. This is not a realistic implementation. Clever project managers first deploy the infrastructure which include the data network, call controller and digital gateways, followed by the roll-out of the training and desktop devices in lumpy groups of perhaps 100 users at a time.

IP phones can function on the same desk as the standard PBX phones. As training occurs and user anxiety diminishes, the legacy phones and PBX can be decommissioned.

The term "overlay" is derived from the way a tablecloth covers the table surface, providing a smooth and clean basis for doing work, without regard to the wood below the cloth. In the same way, the overlay strategy covers the legacy PBX infrastructure with IP and enables new applications without serious regard to the legacy system.

Companies consider this option because they can`t control other factors such as depreciation schedules on existing equipment, higher investment priorities, or a skills gap in assembled network implementation, each of which pose notable challenges to an IP telephony project.

The overlap option allows a company to quickly extract value from the applications enabled by an IP telephony infrastructure without necessarily deploying IP telephony servers.

In complex environments, some of these strategies are implemented at the same time. Each decision-making unit has to consider the risk, cost and applications impact for their operation and business.

It is within this context rather than by strategic design that an enterprise might deploy a combination of these strategies.

There are many ways to implement IP telephony, however, IT architects and network designers need to proceed with caution and work with companies that understand the fundamentals of not only telephony, but more importantly the potential and value of it. Indeed, careful selection and implementation is critical to adhere to the high expectations of users and customers.