VoIP is a considerably extensive upgrade to telecommunication as we know it. There is a lot of difference between PSTN and VoIP phone system. However, the user experience of calling remains the same. VoIP phone system is a technology on which future communication system of the world will be built and soon everyone will switch over to VoIP. There is a difference between VoIP and the traditional landline phones. Traditional landline phones work on copper lines to transmit calls whereas VoIP transmits calls over the internet. The PSTN system depends on the circuit switch technology which remains unchanged. However, there are improvements and efficiencies but the fundamentals remain the same.
PSTN – TDM Circuit Switching
Whenever a call is placed from a phone with PSTN, then the circuits connect throughout the call from one end to the other. This connection needs to be maintained throughout the call despite the distance whether of a few miles or thousands of kilometers. Therefore, users pay high charges for long distance calls or international calls. Additionally, several operators charge interconnection fees when competitors eliminate calls on their network that differ extremely for international calls. It is like the user rents a portion of the phone infrastructure for some time.
That why long-distance calls are so expensive!
Phone carriers invest big capital while laying down lines even in the remote corners. Therefore, distance has a huge effect on how calls are charged. This is the reason for area codes that operators utilize it as the basis to charge the calls.
VoIP – Data Packet Switching
Alternatively, VoIP depends on the same packet switch technology which powers the internet. In this process the voice signals are converted into data packets, every packet has a part of the content along with the address of the final location.
These separate packets are then sent via several hops over different servers till they arrive at the device on the other end. These packets are then reassembled according to the packet instructions then transformed into voice signals that can be heard as words by the person on the other end of the call.
As these packets are transmitted separately and every packet takes a different route to the destination, then there is no requirement to complete the connection between two ends in a call. Basically, this process makes VoIP phone system a lot cheaper than compared to the traditional phone system, especially for long distance calls.
Why Connect VoIP and PSTN Networks?
As it is clear that the basic technology on which VoIP works is a lot different from PSTN. Calls made from VoIP to another VoIP number are very easy to make regardless of which device is used for calling.
You can make VoIP calls through the computer, Smartphone or tablet also form the IP phone to a mobile device. Every call is either free or very cheap as the data does not travel over the PSTN at any point.
Nevertheless, landline numbers are still operational today and people who use VoIP will have to make calls to landlines. Not everyone will be using VoIP and so one person will have to use a landline to make a call.
The same is true for businesses that have to contact, clientele or suppliers who do not utilize VoIP. Even though the other party is using VoIP, they might be traveling to a place where landline offers the just means of access. These situations are not unusual even in countries where VoIP usage is tremendously high.
How to Connect Different Technologies
When you make a VoIP call to a landline number, the call travels for a part-time over the PSTN. The time of the call spent on the PSTN determines the charges of the call (separately from the basic charges of VoIP to VoIP calls). The point where call enters the PSTN this process is called address translation. This means that the IP address is translated into the identifying phone number of the caller to complete the call. It is a lot like the process which is used to covert email IDs and the website links to the IP addresses on the internet.
As VoIP uses the packet switch technology, each VoIP device which is connected to the internet is assigned its own individual IP address. When you call from one VoIP number to another VoIP number there is no requirement for the address translation as both pieces of equipment are identified by their IP addresses. Nonetheless, when you call from a landline, the address translation is a must requirement as a bridge between the IP addresses and phone numbers.
Different Rates for VoIP – VoIP and VoIP – Landline Calls
The most famous VoIP services like Skype usually offer free calls to other users on the same network, only if a computer or other mobile devices are used to make VoIP calls.
The calls made to landline numbers are usually charged more and are separately billed because the portion of the call travels over PSTN. As people adopt VoIP phone system the amount of calls that have to be terminated on the PSTN is falling every day. Even in areas where people are using landlines, most of the phone operators are switching the basic infrastructure to VoIP phone system. It relieves them of the weight of keeping up the aging copper networks that can frequently need costly repairs. Along with the growing recognition of mobile VoIP applications and services, fewer calls are made to regular landlines.
However, it will be soon when all PSTN networks are phased out in all countries and VoIP becomes the standard.