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A T1 phone is when your T1 line is used as a phone line. T1s used for phone service basically fall into two categories: access and tie line. Phone Access T1s are used for voice trunks or lines between a customer's PBX or Key system and the serving local carrier. Tie-Line applications are where two locations either share a PBX and the smaller location is switched by the main location, or they may both have PBXs and a T1 is provisioned between the two for up to 24 trunks of interconnect capacity. In terms of money, the break-even point for individual loops (required for lines and trunks) vs. an access T1 is generally in the 8-10 line range, significant savings can be achieved for installations that require 11-24 voice lines. The access cost is fixed, no matter whether the T1 is fully "loaded" with phone traffic or not, so anything above break-even (8-10) is considered savings. Thus, a T1 phone line can be an economically viable option when enough voice lines are set up. Equipment Choices. In either the access or tie line configuration, T1s can terminate to PBXs either via analog or digital interfaces. Typically, analog interfaces on PBXs have 4 ports, requiring 6 trunk cards to terminate a T1, plus for the digital to analog conversion, a channel bank with the appropriate cards per channel are required. A much simpler equipment option to terminate a T1 of phone service is using a DTI (Direct Termination Interface) card, which is an option for today's digital PBXs. A DTI card will terminate the T1 directly, eliminating any analog conversions (until the call reaches the telephone handset) and the extra space required for channel banks. |
T1 Phone
