T1 PRI For PBX Telephony
A T1 PRI, also called an ISDN PRI, is a "Primary Rate Interface"
providing 23 individual digitized telephone lines plus data such
as Caller ID on a single digital telephone trunk line. A PRI line
is usually much less expensive than a dozen or more analog business
Channelized and Unchannelized
A T1 line may be configured as a single large pipe offering 1.5
Mbps data transport or as 24 individual channels of 64 Kbps each,
ideal for use as individual outside telephone lines to support
Key or PBX business telephone systems.
Channelized T1 vs ISDN PRI
T1 lines can support two protocols of switched circuit telephony.
Channelized T1 lines offer 24 phone lines using in-band signaling.
ISDN PRI, or Primary Rate Interface, offers 23 phone lines and
common channel signaling that can include data such as ANI Automatic
Number Identification or Caller ID.
Fractional T1 Service as a
Not all businesses need the full 1.5 Mbps of a T1 line, but want
higher availability and the dedicated bandwidth offered by T-carrier
digital service. In many cases, fractional T1 services offers
a fraction of the bandwidth at a lowered monthly lease price.
Fractional T3 service may also be available for bandwidth needs
between 1.5 and 45 Mbps.
T-Carriers Offer Digital Telephony
T-Carriers, which include both T1 and T3 lines, offer digital
telephone trunking with multiple phone calls on a single physical
circuit. T1 lines can support up to 24 simultaneous phone calls.
T3 lines have 28 times the bandwidth of T1 lines and can offer
up to 672 simultaneous phone calls for large enterprise or call