Internet Protocol Private Branch eXchange, in short it is known as IP PBX, and Softswitch has some basic differences between them. When a system is called to be an IP PBX, it normally shows that the system is used only to support any PTSN through some SIP trunks or some VoIP, which stands for Voice over Internet Protocol, communication device. There are many IP PBX systems that are already established and a few are still emerging in the field of telecommunication.
A Softswitch is just a feature of the IP PBX that usually derives the important functions of this software. Calling, voicemail, call management, conferencing and many more are the features of Softswitch, with which the hardware and software can be aligned to in a special design by connecting to other device or PTSN specifically. All Softswitch facilities are more or less based on the IP PBX system, as it is the easiest way to avoid any kind of appeal to some specific hardware.
There are many Softswitch facilities, which perform as complete IP PBX running on the standard PC server or hardware. Communication with the PTSN is purely done via VoIP stack that is solely based on software applications.
However, not all the IP PBX systems are Softswitch. The reason behind this is that all the IP PBX systems services are based on hardware used.
The main goal of the IP PBX is to:
It routes all the mobile calls which are within the IP PBX system.
It specifies all the TDM calls of the telecoms, which are based on the Internet Protocol to interface with the PTSN switch or some others.
The important aims of the Softswitch, according to International Softswitch Consortium, are:
Manage the services of the connectivity to the media gateway or some local Internet Protocol endpoints.
The process are selected, in order to accept invitation from other users
It helps to route and transfer the calls by staying within the network when it is signalled by the database users.
It can also control the transfer of any call to other network elements.
Provides an interface, which can support the management functions like billing errors, delivery and many more.
Thus to sum it up, switch software is far superior to IP PBX system based on the system and functionalities, which are provided by each of them.