Getting top performance from a cloud-based or on-site Internet protocol (IP) phone system requires a thorough assessment of your network to get it ready to handle voice traffic. Failure to be proactive can result in a bad experience for users at both ends of the conversation.

The goal of voice over IP (VoIP) is to transport voice in exactly the same format as any other data application — as packets running over an IP network. Your existing local area network-wide area network (LAN-WAN) infrastructure first needs to be assessed to see if it can handle voice and its real-time performance requirements.

To ensure that conversations are loud and clear, steps must be taken to eliminate any problems that could make it difficult to establish call connections and sustain excellent call quality. This typically involves taking a close look at network performance, making adjustments and properly configuring the IP phone system, switches, routers and firewall.

Baseline Network Performance

A business VoIP network assessment begins with assembling a baseline of the existing network that will include the kinds of applications running on the network as well as the current traffic volume. A device with “packet sniffer” software is used to gather this kind of information.

After a network baseline is assembled, a traffic simulator is used on the network after normal business hours. The traffic simulator will put the collected baseline data traffic on the network and add voice traffic, including peak-hour traffic, to determine its impact on overall network performance.

Quality of Service

Two critical items revealed by the assessment are the number of concurrent voice calls the network can handle without bogging down other applications, and the quality of the voice conversations. If the quality of the voice conversations falls below accepted industry standards, the network must be fine-tuned to better handle voice. Too much delay or clipped speech will disrupt the natural rhythm of a phone conversation.

The traffic simulator might start out by placing 25 voice calls on the local area network. As the number of calls increases, voice quality can be impacted, so an optimal balance must be achieved to arrive at the true call handling capacity of the network.

Striking this balance involves introducing Quality of Service (QoS) into the network during the assessment phase. The objective is to change the behavior of the network so that data and voice traffic are optimized to share the available bandwidth.

Switch Settings

Changing the settings of the LAN switches classifies all the network traffic and marks the different traffic types with their own priority levels. Voice will have first crack at the bandwidth, since it is a real-time application. Data applications are next in line, starting with database access, followed by HTTP for Internet access and FTP for file transfers, with e-mail getting whatever bandwidth is left for best-effort delivery.

Router Settings

The network assessment also includes the routers at each office location that handle voice packets over the WAN. This is important because today’s LANs operate at 1,000 megabits per second (Mbps) or more, whereas a WAN connection may be much slower. Concurrent voice calls on the LAN may exceed the number of concurrent calls that can be supported on the WAN.

As with the LANs at each office location, an assessment is made of the volume and kinds of applications that traverse the WAN, and then simulated voice traffic is introduced to check its performance against industry standards.

Firewall Settings

Sometimes a firewall will be set to enforce strong security measures to protect the internal network. This may block both phone signals and voice traffic. This issue is overcome by opening specific port ranges to allow signaling and voice traffic to securely pass through the firewall.

Deploying the System

Typically, voice traffic on the WAN will be going through the network routers of different carriers and Internet service providers. Maintaining consistent voice quality requires everyone’s cooperation. Their network routers must enforce the same Quality of Service settings that are established on your office routers.

This is no longer as problematic as in the early days of VoIP. Today, the handshaking processes between the network devices determine the best way to handle the different types of traffic offered to them with the result that voice will get priority treatment.

A thorough VoIP readiness assessment will reveal all the potential performance problems before your VoIP service or equipment is deployed, as well as any hidden costs associated with upgrades needed to ensure the proper performance of voice. Preparing the network for VoIP provides peace of mind and the assurance of a successful implementation.

Jeff Nolte is president of Chesapeake Telephone Systems ( in Millersville. He can be reached at 410-850-4848 or [email protected].