voip advantages and disadvantages

What are voip advantages and disadvantages ?

VoIp is a new communication technology which uses legacy IP network for Voice and other multimedia services. Service providers offers voip services via SIP trunk. Like many other technologies , it brings some advantages and disadvantages.  We have already discussed  in previous post about the VoIP call. In this tutorial we will discuss about the VoIP advantages and disadvantages in details with examples.

Voip Advantages :

Here are the advantages of the VOIP over legacy telephone system. Each section have detail explanation alone with a suitable example. The advantages not limits to the ones mentioned here, there can be more. But these are major one.

Coverage :

The  most important thing in any communication network is the coverage. Coverage means , geographical area covered. If a network is very strong, but provide coverage only in limited area,  is not good for the service provider or end user. PSTN covers only the areas those are covered by a telecom operators over wireless channels or via telephone lines.  Voip have advantage, that it can work over a telephone network internet connection and also on other internet provider network. E.g a good broadband IP network can bring an extra coverage alone with telephone company coverage. Mobile operators also realize the advantages of voip by using an internet connection option for the services. This leads to the service like  Wifi Calling , femtocell  and picocell. These uses in house radio channels and telephone towers.


For a caller, the  cost matters a lot. These days cost for local calls and national roaming has been reduced significantly. Almost all mobile operators offering a fix price plan for unlimited voice calls and sms with in a country. But when it comes to international calling or roaming. The cost is still significant. Voip provides cost advantage.  Event few voip companies e.g skype , provides free Voip to Voip calling via mobile or web app.  They also provides calling from Voip phone to any other GSM mobile number. This adds some cost but still you may find cheaper than normal GSM to GSM international calls. Along with this calling card is also a good example. Where calls rate are local  with some amount from calling cards.

Initial Setup Cost:

The mobile network setup,  costs to the companies those providing voice services. When they need to give a PSTN connection , there should be a lines from local telephone exchange to the subscriber home or office.  Voip uses already deployed internet connection. In case of Voip initial setup cost is almost zero for network infrastructure. Only the cost will be of handset (if not a mobile app you are using) and a top up from the Voip service provider.

Redundancy or High Availability:

Mobile or a PSTN phone connects to a single point of connection to the telecom operator. The single point of connection is the local telephone exchange.  Imagine , if telephone exchange got the power failure for a significant period of time. During that there will not be any service. Here VoiP have an advantage of redundancy.  Redundancy means multiple points of contact. There can be multiple voip back-end servers located at various far places. If one can not serve , other can provide services.  Voip phones have server name as an URL (e.g www.voipprovide.com) in voip provider or server configuration. The URL points to a voip server IP by doing DNS lookup.  When a server fails (to which URL was pointing ), only DNS entry needs to 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 the fix capacity. While the internet is moving towards the much more faster communication channels. For example , many internet providers are providing fiber optics for connectivity. This enables good quality voice and video calls.

Voip Disadvantages:

Above section explains about the voip advantages. Now there are few disadvantages also. Following mentions the disadvantages for the voip.

No Dedicated Bandwidth:

Although internet have 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 the VoIP . This may result in the poor quality of calls. For example you might experienced that sometimes , voip call quality is good , and some time not. It is not only your internet connection speed which 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 the Austria, with a good quality of internet speed.  But the link of 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 each and every hope from calling to called phone.

The PSTN contrast to 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 do not routes all the way over the VoiP provider network only . It also uses public internet connection one the way. This is a disadvantage for the security in general.  The local government body can not trace the voip call. While PSTN calls are always via telecom operators , so the call can be traced.

Special Software's are required:

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


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