what is the difference between the public switchand pabx .
i know they are meant for different market segments and size
but now some vendors are offering the public switches in the same capacity and sizes as the pabx and they claim that there is no difference between the two.
a public switch is a switch where the public can be connected whiles the pabx is private switch. there are some techicanl diffrences however depending on the usage there is not much diffrence and a pabx can be used for a public switch.
A major difference between PABXs and Public Switches is scalability. A Telco Class Switch (5ESS like) can be expanded up to 250.000 local circuits, 75.000 tandem circuits or a mix of them. Also can handle about 2.5 Millions BHCalls, with the CPU expanded at it`s limits.
More than 30.000 Erlangs can be managed, with the last generation circuit switched exchanges. Many other services can be provided concurrently, like ISDN, VoIP, IN, etc. Billing capabilities are awesome.