The Quality of Your VOIP Solution Lies With the Weakest Link

By: Steve Norris

The most reliable of all VOIP (Voice Over Internet Protocol) solutions will always perform in accordance with the quality of the data connection involved. In determining just how well your proposed VOIP solution will work for you, look no further than your weakest data connection.

Whether you are looking for a hosted VOIP PBX solution, implementing remote IP telephones or Softphones connected to the office via VPN, connecting multiple offices via T-1 or fiber, or just using VOIP telephone service, the common denominator that dictates your quality of voice service is your data connection. Since Voice Over IP is a data protocol, it only makes sense that the quality of your service will be dictated by the strength of your data connection. Your voice conversations require uninterrupted bandwidth of up to 90k each in order to perform with the same quality that has come to be expected from traditional analog or digital phone service. Not having the available bandwidth or uninterrupted bandwidth needed will cause poor results.

The most common methods of commercial VOIP applications seen are connecting offices together via data connections and connecting remote users to the on premise telephone system. Both applications have tremendous financial and efficiency benefits, but only if they can be implemented with quality of service. The ability to share resources such as a common receptionist, the ability to bypass toll charges by using IP, the ability to connect remote workers, track results, and to attract top talent with flexibility and state of the art technology all have tremendous monetary benefits to the implementing company. However, special care must be used in selecting the data connections used in order to implement the solution successfully.

We take a look at the various types of data connections available for these applications, and look at the weakest link in the solution.

ADSL
SDSL
Cable
Wireless
Fractional T-1, T-1, Bonded T-1, DS3, OC
Point to Point T-1
Frame Relay
Fiber Optic

We will take a look at the asymmetrical connections first, as they tend to be the most unreliable. Asymmetrical data connections include standard residential quality DSL, some business DSL, Cable internet, Satellite internet, and Microwave internet. In most of these cases, the download speed will often greatly exceed the upload speed. For instance, it is not unusual to see a DSL package listed at up to 1.5 M download, and up to 384k upload. "Up to" being the key. You never get full speed, and it can often be quite a bit less. A speed test will be in order during several parts of the day to test for speed and network variations. DSL typically offers no guarantees of service levels or uptime, and as a shared network, speeds will fluctuate throughout the day. Web traffic must be carefully monitored if you are using your data connection for voice applications, as it is common for voice conversations to be interrupted with data traffic if QoS routers are not in place.
ADSL circuits also tend to suffer from more jitter and latency than other types of high quality data circuits, so if this solution is used to connect remote users of offices, it is imperative to have a VPN router on both sides of the connection to ensure the best possible quality. Some downtime is to be expected on an annual basis, but it can be a tremendously cost effective connection option. Wireless options such as satellite or microwave are never suggested, as there is typically too much latency involved to maintain call integrity. ADSL is not typically recommended for a location with more than 1-2 users. ADSL is never recommended for a hosted solution.

SDSL, or symmetrical DSL, is a preferable option over ADSL. This type of connection offers users the same upload and download speeds, and it is typically a business class circuit that comes with some quality guarantees. Often speeds are seen such as 1.5M down/1.5M up. 768k down/768k up. Preferable over ADSL options, but also much more costly. For some companies, this would be a minimum acceptable solution for a location with multiple users.

Fractional T-1, T-1, Bonded T-1, DS3, OC: All of the T-1 varieties of service and greater are tremendous options for VOIP solutions. All Fraction T-1 circuits and above have been thoroughly tested over time, and they provide end users with a tremendously reliable solution. With symmetrical data solutions typically starting at 384k and up, T-1's have a guaranteed uptime unmatched by other available data circuits besides fiber. Voice Prioritization is still required at either the network level via MPLS or at the end user level when connecting offices. Voice conversations must always have priority over bursts of data traffic in order to maintain optimum call quality.

Point to Point T-1's: As one of the most preferred methods of connecting offices, Point to Point T-1's offer superior reliability and keep your voice traffic from competing with unpredictable internet or carrier network traffic. Point to Point T-1's require routers with QoS, CSU/DSU, and can be quite an investment up front, but they provide tremendous quality and uptime. By bypassing the carrier data network altogether, you are assured of a dedicated connection between your sites to be used only as you prefer. Depending on the size of the connection, offices with dozens or hundreds of people can be set up to operate off of Point to Point T-1 circuits without requiring local dial tone.

Frame Relay: If your network utilizes Frame Relay, it is not recommended to run voice services over it. Frame was never designed to support voice traffic, and there are much better and more cost effective options to choose from.

Fiber Optic. Fiber being available for direct connection or for point to point applications is becoming more and more common. Some residential varieties such as FIOS from Verizon are of an asymmetrical nature, but typically still provide plenty of reliable bandwidth to support remote users. Commercial fiber options can bypass all traditional points of failure on standard networks and can provide the best possible VOIP connection solution. Fiber bypasses the local ILEC in most cases, and it gives you a clean clear connection straight to the carrier central office. With high traffic volume capabilities and superior clarity and reliability, fiber has come to the forefront as the preferred medium for VOIP solutions. Fiber is not always cost effective, but the quality results are undeniable.

When selecting the medium or circuits that will support your VOIP solution, understand that the main limitation to quality you will experience will be the weakest link in your data network. If your main location has a T-1, but your remote users with IP phones have an ADSL circuit, your weakest link lies in the ADSL circuit. If you are going to experience quality issues, it will most likely occur there. If your main location has a bonded T-1 or DS3, but your remote warehouse has Cable internet, your weakest link will be your Cable connection. As always, work with your local telecommunications professional to determine the best and most cost effective data circuits to use when implementing a business grade VOIP solution.

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