Global One’s ISDN PRI service provides full-featured, 2-way connectivity between ISDN compatible PBX or Key Systems and the Public Switched Telephone Network (PSTN).
ISDN (Integrated Services Digital Network) PRI (Primary Rate Interface) offers access to a telecom infrastructure that can dynamically adapt to the changing needs of your business. ISDN PRIs digital nature as well as its ability to dynamically partition itself to accommodate multiple types of incoming and outgoing calls, enables the simultaneous high-speed transmission of both voice and data over a single pipe.
How ISDN PRI Works
ISDN PRI pipes are designed over a standard T1. They are partitioned into 23B channels and 1D channel. The D channel acts as the “brain” of the pipe where the B (bearer) channels are responsible for carrying the information payload. This segregation of D and B channels is known as “Out of Band Signaling” and is the reason for ISDN PRIs versatility. Other technologies such as Digital Trunk and Business Trunk will have “In-band Signaling” which is not quite as efficient since it reduces the bearer channels delivery to 56kbps and requires line cards for each port. B channels in a PRI can carry 64 kbps of information. Only one B channel is required to establish a telephone connection. Some data files may be too big to transmit effectively on just 1 B channel; ISDN PRI allows for multiple B channels to be dynamically “bound”, allowing the customer to capitalize on the carrying capacity of the combined channels. When the information has been sent the B channels are automatically “unbound” and made available to other users.