What are VoIP’s advantages and disadvantages?

VoIP is a new communication technology that uses the legacy IP network for voice and other multimedia services. Service providers offer VoIP services via SIP trunk. Like many other technologies, it brings some advantages and disadvantages. 

We have already discussed in the previous post about the VoIP call. In this tutorial, we will discuss the VoIP advantages and disadvantages in detail with examples.

VoIP Advantages :

Here are describing the advantages of the VOIP over the legacy telephone system. Each section has a detailed explanation, along with a suitable example. The benefits do not limit to the ones mentioned here. There can be more. But these are the major ones.

Coverage :

An essential thing in any communication network is coverage. Coverage means the geographical area covered. If a network is robust but provides coverage only in a limited area, it is not helpful for the service provider or end-user. PSTN covers only the areas that are covered by a telecom operator over wireless channels or via telephone lines. VOIP has the advantage that it can work over a mobile internet connection and also on other internet provider networks. E.g., a good broadband IP network can bring extra coverage along with telephone company coverage. Mobile operators also realize the advantages of VoIP by using an internet connection option for the services. This leads to services like wifi Calling, femtocell, and picocell. These use in-house radio channels and telephone towers.


For a caller, the cost matters a lot. The cost of local calls and national roaming has been reduced significantly these days. Nowadays, almost all mobile operators offer a fixed-price plan for unlimited voice calls and SMS within a country. But when it comes to international calling or roaming. The cost is still high. VoIP provides a cost advantage. 

Even a few VoIP companies, e.g., skype, provide free VoIP to VoIP calling via mobile or web app. They also offer to call from a VoIP phone to any other GSM mobile number. This adds some cost, but still, you may find a cheaper option than regular GSM to GSM international calls. Along with this, calling card is also a good example where the call rate is local with some amount from calling cards.

Initial Setup Cost:

To set up a network, there is a cost for network setup for the mobile operators. When they need to give a PSTN connection, there should be a line from the local telephone exchange to the subscriber’s home or office. VoIP uses an already deployed internet connection. In the case of VoIP, the initial setup cost is almost zero for network infrastructure. Only the price of the handset (if not a mobile app you are using) and a top-up from the VoIP service provider.

Redundancy or High Availability:

A Mobile or a PSTN phone connects to a single connection point to the telecom operator. The only point of contact is the local telephone exchange. Imagine if a telephone exchange got a power failure for a significant period. During that, there will not be any service. Here VoIP has the advantage of redundancy. Redundancy means multiple points of contact. There can be various VoIP back-end servers located at different far places. If one can not serve, others can provide services. VoIP phones have the server name as a URL (e.g., www.voipprovide.com) in the VoIP provider or server configuration. The URL points to a VoIP server IP by doing a DNS lookup. When a server fails (to which the URL was pointing ), only the DNS entry must be updated to the new VoIP server. This way, VoIP service will continue in case of failure.


The capacity refers to the amount of data a network can carry. The traditional phone lines are copper wires and have a fixed capacity. At the same time, the internet is moving towards much faster communication channels. For example, many internet providers are providing Fiber optics for connectivity. This enables high-quality voice and video calls.

VoIP Disadvantages:

The above section explains the VoIP advantages. Now there are a few disadvantages also. The following mentions the disadvantages of VoIP.

No Dedicated Bandwidth:

Although the internet has a high bandwidth, but it is a shared packet-based network. This is a disadvantage for VoIP. There is no way to give a dedicated speed to VoIP. This may result in a poor quality of calls. For example, you might experience that sometimes, VoIP call quality is good, sometimes not. It is not only your internet connection speed that decides the call quality. But also the available bandwidth on intermediate network routers/switches and other connectives.

For example, if you are making a VoIP call from India to Austria, with a good quality internet speed. But the link to the internet between India and Austria is poor. In that case, the call quality will be poor. This concludes that the internet speed should be good at every hope from calling to the called.

The PSTN contrasts this. When there is a call, a dedicated channel (TDM Trunk E1/T1) is reserved for the call only. Make a guaranteed quality of service.


A VoIP call does not route over the VoIP provider network only. It also uses a public internet connection on the way. This is a disadvantage for security in general. The local government body can not trace the VoIP call. While PSTN calls are always via telecom operators, the call can be traced.

Special software applications are required:

By default, mobile devices or PCs don’t have support for VOIP. A user has to install a third-party application. This application may pose a security threat, as it can access the device’s data. With LTE, there are features, e.g., wifi Calling. But still, it is not supported by all mobile operators. So before using a VoIP client, choose a trusted service provider.