Implementing VoIP - Major Migration Issues

Written by: Curtis S. Burnside, CCNA, CIW - Nov 22, 2008

The major migration issues for a small to midsize business surround:

1. A quality network or Internet connection assuring not only uptime reliability but also voice clarity. 2. Service level agreements (SLA) that assure the service provider selected will deliver on their promise. 3. Coordinating existing telephone equipment into the VoIP initiative. 4. Assuring a clear migration or integration path for remote workers and additional branch offices.

Let's take these items one and a time.

A quality network or Internet connection -- although a small office of five handsets or less might well be served utilizing an ADSL or cable modem Internet connection, these types of small, best effort connections will be ill-suited for a larger deployment, primarily due to network congestion, half duplex and ISP oversubscription issues.

Many people don't realize that just because you have an advertised "massive bandwidth" downstream bit rate like 3, 6 or 10 Mbps, this doesn't necessarily mean that the quality of the connection is adequate to support real-time upstream requirements for protocols such as VoIP.

In a general sense what's generally needed is an adequate sized Internet pipe from a quality service provider that provides for either an SLA or at least an end to end QOS metric. This then assures the voice packets arrive in order and as close to real time as possible. It should be noted that even with a quality provider with its own Tier 1 IP backbone such as AT&T, Sprint or Qwest that the Internet is a public place rife with latency and delay.

Service provider selection in VoIP network design are of tantamount importance when implementing Voice Over IP.

So what's generally needed for larger offices is to select a quality 4 wire, full-duplex T1 or better class of service preferably from a tier 1 provider or a resale of such.