After publishing of our article about Demarcation Points, which briefly discussed also concept about PBX, and this scheme below, one of our readers asked us an interesting question:

 

 

 

 

 

 

 

 

What’s the difference between PBX and PABX? Is it same or no?

 

 

Well, answer is – Yes and No.

 

Yes, in the context that nowadays, these terms are perfectly interchangable and either one you want to use is OK.

 

Then, why two of them, and what is the difference?

 

Well, in the beginning, PBX – Private Brunch Exchange were made like a board of jacks terminating loops and PBX trunks, and physical person – operator were sitting and plugging and out jacks to make necessary connections.

 

 

 

 

 

Figure 1: “Manual” PBX

 

 

Later on, computer based PBX-es were invented, and in this case A- means Automated, PABX stands for Private Automated Branch Exchange.

 

 

So, at that moment these 2 terms were used simultaneosly, however, now, mostly term PBX is used, and it means still of course fully automated hardware based system.