Implementing VoIP - Important SMB Considerations

Written by: Curtis S. Burnside, CCNA, CIW - Dec 4, 2008

Many small and midsize business owners have heard about voice over IP or VoIP as a great way to save money on both local calling and long distance charges as well.

There are a number of issues to consider when looking at implementing VoIP, not the least of which is network reliability and assuring that telephone calls are close to "toll quality" and not being dropped or callers being cut off.

Because VoIP calls utilize a data connection or Internet connection rather than the public switched telephone network (PSTN) these calls are at the mercy of what many times is a best effort network. Business owners and customers alike who have become used to toll quality calls utilizing the PSTN are many times gravely disappointed with dropped calls, perhaps sounding like Darth Vader from time to time, as well as unconnected or misdirected calls.

In the event the business has multiple branch locations and is hoping to the erase long-distance toll for intra-company calling, and might also require a high-speed IP backbone for its own intra-company data initiatives, then a telecommunications broker or service provider should be approached to design a private IP backbone, which are surprisingly affordable in this day and age. The customer business can then leverage this backbone for other high speed data traffic such as SQL applications, e-mail, Internet browsing and file transfers etc.

SLAs Service-Level Agreements generally have four major components with regard to voice over IP initiatives. Unfortunately many service providers do not provide a "jitter" SLA metric which can be of increasing importance depending on the class of service desired and the number of users and business locations.

Let's then look at the acceptable tolerances for measuring the SLAs required for an SMB VoIP initiative.

Latency -- measures the time it takes for IP packets to travel one way between points in the service providers network, generally measured in milliseconds, this metric should be less than 50ms, with superior service being less than 40ms.

Jitter -- measures the difference in time it takes for two IP packets to travel between points in the network. If provided, this metric should be less than 5ms – 10ms, with superior service being less than 2ms.

Packet loss -- measures the number of IP packets dropped as they traverse the service provider's network. This metric should be less than 1% with superior service being less than .5% of the total packets.

Meantime to repair (MTR) -- this is the time period the service provider commits to repairing a downed or impaired circuit. Obviously extremely important when the majority of your voice traffic is being carried via VoIP. Most quality service providers should be able to commit to a four hour or less MTR. Additionally, provisioning options which allow for a “fully managed router” or VoIP gateway on your T1 connection are very affordable and allow the service provider to constantly monitor the status of the connection, this allows the provider to initiate repairs even when you as a customer may not be aware of a downed or impaired circuit condition.

Coordinating Existing Equipment & Assuring a Clear Migration --

Depending on your current equipment configuration you may or may not desire to keep your equipment. The choice of whether to use your existing equipment, purchase IP enabled equipment or perhaps utilize a "Hosted PBX" solution will be a major determining factor in your ongoing migration plan and quality of service.