When planning for VoIP, re-evaluate the networks and backups

Enterprise Networks & Servers, Sep 2005 by Shacklett, Mary

Voice over IP technology (VoIP) will play a greater role in network solutions over the next three years, but few companies are opting for an all-out replacement of their existing telephony assets. Instead, they are "picking their spots" for VoIP, developing a hybrid approach that combines elements of VoIP and already-established telephony technology, and slowly orchestrating a migration to more IP-based solutions when assets retire and new business needs arise.

This article discusses fundamental approaches to VoIP planning, design and implementation for sites interested in adopting a hybrid approach to their telephony deployment.

Sound economics

Many sites are pursuing a gradual rate of VoIP adoption for two main reasons:

* VoIP is still a new technology, and as a new technology will demand new implementation, quality metrics and support standards from internal IT;

* VoIP potentially displaces existing telephony assets that are very expensive, and that have equipment life cycles and contracts that must run to their natural ends.

Common application areas for VoIP are VoIP capability for field-based employees; VoIP enablement of branch offices; and VoIP networks between remote offices and between remote offices and headquarters. VoIP works in these scenarios because phone systems in branch offices are often outdated and they require replacement; and mobile employees cannot gain the flexibility they need with traditional telephony.

One common VoIP implementation strategy companies are taking uses a mix of both VoIP and traditional telephony phonesets, while VoIP-enabling the networks and the PBX.

At the PBX, administration of this mixed technology environment can be achieved by adding the necessary hardware for VoIP, and by converting the PBX to a hybrid box that can support both VoIP and traditional TDM (time division multiplexing) telephony. This mixed strategy of VoIP and traditional telephony allows for effective asset management to the end of asset depreciation cycles - and it allows IT to adapt to changing technology support requirements.

Network planning and design

The keys to sound VoIP network planning is solid design and strong implementation. The result of an excellent network design is an infrastructure platform that will serve the enterprise for years. To realize both goals, sites should begin any VoIP migration process with a thorough assessment of existing corporate networks.

This process often begins with a network assessment that evaluates network readiness for the expansion of IP technology. Minimally, this means that the network must be fully functional and IPenabled on a 9-to-5 basis, and that appropriate redundancy is already built in to allow for failover and the continuation of normal business operations. In most cases, whether the network uses standard TDM or VoIP technology - or a combination of both - adequate redundancy means that the network must have "fallback" capability to PSTN (public switched telephone network).

A network assessment for VoIP readiness should focus on the following areas:

* Transmission speeds;

* Peak traffic;

* Network availability; and

* Protocol used.

You should also know where your "pain points" are likely to be. For example, if you are a bank that has a central server at headquarters and you also have distributed branches with communications that flow over an IP services provider's router, what happens if the services provider's router shuts down? There should be another means of rerouting communications, and of doing it seamlessly, to avoid both customer and employee quality of service issues.

It is equally important to perform as complete a simulation of your new hybrid network's performance as you can possibly do - before going live. The gateways between your traditional and VoIP technology are especially critical to evaluate for performance-as is performance during a primary communications path outage (failover). IT staff with a background in data communications may not fully understand the significance of the failover requirements in a voice environment. Voice communications need to be reliable to five 9's (uptime of 99.999 percent). This uptime level has not necessarily been a past requirement for data. One way to guarantee 99.999 percent uptime performance is to have a "back door" to PSTN service if everything fails.

Finally, plan for foreseeable issues. If you are working with a VoIP vendor (and you probably will be), ask the vendor for information about what he has seen in the field when it comes to pitfalls. One possibility is phone "echo" that can emanate from the network. Another major area to manage is business expectations within your enterprise. Most vendors have a return on investment (ROI) or a cost model that they will prepare for you. Ask them to do this, and to plug in your numbers. When they tell you that your payback will be within 12 months of implementation and that you will eliminate countless landlines and long distance charges, take the time to thoroughly understand the logic behind the numbers to see if you agree with it. If you can't clearly and cogently explain this cost model to your upper management, chances are that it is flawed.