Difference Between a Truck and a Subscriber Trunk

Question

I know a trunk is the line that connects PBXs or connects a PBX to a telecommunication subscriber service. Hence, What is the difference between a trunk and a subscriber trunk?

Answer 1

It sounds like a vendor specific name for as trunk. In 5+ years, I have only seen a few "types" of trunk and they are only split like this by vendors for pricing. The sub-types I have seen are Inbound Only, Outbound Only, Metered/Unmetered, Limited/Unlimited. They are not mutually exclusive. You may see Unlimited Metered Inbound Only. "Metered" means charged by the minute/second/sub-second. Fixed price "trunks" are typically Unmetered, but Limited to XXXXXX seconds. Unmetered, Unlimited is very rare and quite costly.

Answer 2

If "trunk" and "subscriber trunk" are next to each other it might mean that "trunk" = "operator trunk", trunk to next PABX layer or some kind of VoIP proxy.

Answer 3

As others have said, there are no exact definitions for the term, but I would say one logical use would be:

• Trunk - a multiple voice channel link connecting two public switches (telephone exchanges) together
• Subscriber trunk - a multi voice channel connection between a public switch and a subscribers PABX

In the past, most subscribers to a PSTN telephone Network (i.e. a normal public phone network) had a single 'line' allow them to make a single call. Subscribers with their own PABX, such as a business, would often use a trunk type connection rather than having multiple single lines.

Again, none of the above is definitely defined anywhere (that I am aware of) but this interpretation is one I have seen before.