Do you know the difference between a DSS voice circuit and a PRI? Some carriers offer two types of voice T1 circuits, one called a DSS and one called a PRI. Both T1’s offer voice calls with DID’s (Direct Inward Dialing). The circuit that is most commonly known as a DSS circuit offers 24 trunks that in turn can make and receive 24 simultaneous calls. The outgoing calls on a DSS circuit will not show the name of the company making the call, the calls will show up as unknown or out of area with no number associated with the call. The circuit that is known as a PRI, or also called a PRS ISDN circuit, will offer 23 trunks with the 24 trunk being the signaling channel that allows the caller id. Because the 24 trunk is needed to send out the caller id only 23 simultaneous calls can be made or received at one time. The PRI will send out on caller ID the customer name and number that they would like displayed to the calling party. It is important that clients understand the differences from a value perspective as well as what meets their company needs.