PSTN denotes public switch telephone network and the VoIP denotes Voice over Internet Protocol. VoIP phone technology is combined of conjuctive and phone bout. International phone calls and video calls are cheaper when one uses VoIP . The VoIP calls are very much safer and easier to make . It's highly secured network so no other third parties cannot involve and distract the calls.Other than calls it's highly secured to real time usages like location sharing, messages, sharing the information as soon as possible as a document. VoIP is an upgraded version of PSTN. On the other side, PSTN is an old traditional phone method. Here the datas like messages and calls are transferred via copper wire. So here the transmission is much slower when compared to VoIP.
The difference between VoIP and PSTN is based on their way of passing calls. In a VoIP system, the audio is converted into digital data and then it's send over the internet to the other end. I.e no need of physical transmission equipment is not needed in VoIP networkBecause of this advanced technology VoIP is widely used over PSTN. Since internet connection is available everywhere and in all places the growth of VoIP is at the peak level. PSTN is not used because it's much complicated to make phone and video calls whereas VoIP is simpler