A switch that runs in software on a computer. A Software Switch.
I guess you could loosely think of it as VoIP at the CO Level.
Wikipedia - Softswitch Page There's a wikipedia explanation.
Asterisk is one form of a softswitch technically, although it's simultaneous call capability somewhat limits it from using it in that purpose.
I've only had to use NI2 around here and dont have many PRI problems. The only problems I can complain about is that different switches dont necessarily give the same code for the same fault. Makes figuring out why a call hung up interesting.
