Four steps to improve the quality of VoIP services

Application VoIP service quality (QoS) has four key steps. If you do not follow these four steps, your VoIP implementation will not realize its full potential. In addition to enabling the vro function, QoS has many things to do. Therefore, it takes some time for you to plan and design the correct QoS for your speech environment. The following are the four key steps:

Step 1: classify your voice communication

First, you need to select the best solution to mark the packets that require priority processing. Classification includes deciding which data streams can pass and which data streams need to wait. Everyone wants their applications to have the highest priority. However, if you do that, you will not have time to do anything else. QoS is a zero-sum game. In this game, if you get the highest priority, you get the second priority. Because VoIP is a real-time and demanding communication, you need to give it the highest priority level.

The recommended mechanism is to verify the endpoint. The reason for this recommendation is that when the network can verify the IP address of a device, the corresponding device is an authorized IP phone number, the router can also trust the communication priority mark provided by the phone. In this way, you can protect the network to prevent improper use. Endpoint verification can determine which data packet gets a high priority and determine which data packet gets the best effort to support it.

Before your data packets pass, we recommend that you develop a plan to determine which service level will be used for communication, how many service levels are available, and what tags you use for each communication category. You also need to mirror your priority category to the entire layer 2/Layer 2 boundary, and also need to mirror your priority category to your carrier's service products.

Step 2: enable the Service class Mechanism

Now let's turn on the mechanisms in the network routers and switches to prioritize VoIP communication. The important service-class (CoS) mechanism is the DiffServ (Service-differentiated structure) standard used for routing infrastructure and the IEEE 802.1p standard used for switching infrastructure. You should find that it is easy to challenge these devices, because CoS can be started only through the vro and switch configuration files.

Step 3: plan and manage your bandwidth

Next, you will need to understand, plan, and manage your bandwidth. You will find that DiffServ and IEEE 802.1p are not fully functional QoS mechanisms. They provide different levels of services, but they cannot solve the problem of excessive orders. Therefore, in order to ensure that the voice quality is not affected, you need other mechanisms to ensure that you have not subscribed to the service category in excess.

At the same time, providing good VoIP service quality requires you to predict the number of simultaneous calls. Then, you also need to assess whether the available bandwidth will support the demand in the plan, or whether you need more bandwidth. In this regard, the financial reality is an inevitable factor, because your budget may not support your need for bandwidth everywhere. Therefore, you must control the number of users that can access this bandwidth at the same time. In addition, when there is no bandwidth for a phone call, you will receive the same feedback as the public exchange phone call. It should be noted that, this feedback can be seen as a "busy" signal of VoIP.

IP-PBX has this built-in feature. They know the network structure, and they also have parameters that determine the number of simultaneous voice calls allowed between sites. When the network reaches this limit, the IP-PBX may send a busy line signal to the next caller, or transfer the call to another line (like PSTN ).

Step 4: monitor VoIP Performance

In this last step, you need to monitor the performance to know whether your network provides a high-quality transmission and high-quality voice reproduction for the voice stream. If there is a problem, you need to know the problem before your users are dissatisfied. Because of the special needs of speech, you may need to consider using a new monitoring tool.

1. Research on the QoS Architecture of the Next Generation Network VoIP service
2. QoS technology of VoIP in MPLS-Based Integrated Model