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Line Interfaces
The Line Interfaces menu is used to configure the active (enabled) digital communication line interfaces within
the MultiAccess. All MultiAccess units come with four built in digital line interfaces. The first line interface is
enabled by default because all units come pre-installed with one 30-modem module. The three remaining line
interfaces can be activated as needed by installing an MA30EXP port expansion module into the corresponding
position, increasing the number of modems within the unit.
The line interfaces can be set to either E1 or T1 digital line types via software control, however all interfaces
within the unit must be set to the same basic type (all must be T1 or all must be E1). After changing from one
to the other, the MultiAccess requires a reboot.
The following statements attempt to summarize, in the simplest terms, certain digital carrier technology, T1 and
E1 lines, in relationship to the MultiAccess.
T1 and E1 signals are made up of multiple protocols running at multiple levels. Layer 1 refers to the framed
signal physically transmitted and received on the wires (transport layer). Layer 2, runs a signaling, or
messaging protocol that is responsible for communicating, signaling, the establishment of a call between end
points. Layer 2 takes place within certain resources, areas, of the Layer 1 signal.
E1 Digital Line
E1 layer 1- a 32 channel (plus overhead) signal at 2.048 Mbit/s
E1 layer 2 - the MultiAccess supports only one type of E1 signaling method, ISDN_PRI (a.k.a. CCS)
Other methods exist (Like R2 Digital and R2MF), but these are not supported.
T1 Digital Line
T1 Layer 1 - a 24 channel (plus overhead) signal at 1.544 Mbit/s
T1 Layer 2 - the MultiAccess supports two methods of T1 signaling, ISDN_PRI and RBS
RBS (Robbed Bit Signaling) - CAS (Channel Associated Signaling)
ISDN_PRI - CCS (Common Channel Signaling)
MultiAccess Communications Server MA30120 User Guide
Chapter 3 – Software
Line Interfaces
117
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