AudioCodes Mediant 500 E-SBC, User Manual

Page: 346 / 920

User's Manual 346 Document #: LTRT-10437
Mediant 500 E-SBC
The parameter DchConfig_x = Trunk_type defines the type of NFAS trunk. Trunk_type is
set to 0 for the primary trunk, to 1 for the backup trunk, and to 2 for an ordinary NFAS
trunk. ‘x’ denotes the physical trunk ID (0 to the maximum number of trunks). You can also
use the Web interface (see ''Configuring Trunk Settings'' on page
333 ).
For example, to assign the first four T1 trunks to NFAS group #1, in which trunk #0 is the
primary trunk and trunk #1 is the backup trunk, use the following configuration:
NFASGroupNumber_0 = 1
NFASGroupNumber_1 = 1
NFASGroupNumber_2 = 1
NFASGroupNumber_3 = 1
DchConfig_0 = 0
;Primary T1 trunk
DchConfig_1 = 1 ;Backup T1 trunk
DchConfig_2 = 2 ;24 B-channel NFAS trunk
DchConfig_3 = 2 ;24 B-channel NFAS trunk
The NFAS parameters are described in ''PSTN Parameters'' on page 819 .
21.6.1 NFAS Interface ID
Several ISDN switches require an additional configuration parameter per T1 trunk that is
called ‘Interface Identifier’. In NFAS T1 trunks, the Interface Identifier is sent explicitly in
Q.931 Setup / Channel Identification IE for all NFAS trunks, except for the B-channels of
the Primary trunk (see note below).
The Interface ID can be defined per member (T1 trunk) of the NFAS group, and must be
coordinated with the configuration of the Switch. The default value of the Interface ID is
identical to the number of the physical T1 trunk (0 for the first trunk, 1 for the second T1
trunk, and so on, up to the maximum number of trunks).
To define an explicit Interface ID for a T1 trunk (that is different from the default), use the
following parameters:

ISDNIBehavior_x = 512 (x = 0 to the maximum number of trunks identifying the
device's physical trunk)

ISDNNFASInterfaceID_x = ID (x = 0 to 255)
Notes:
•
Usually the Interface Identifier is included in the Q.931 Setup/Channel
Identification IE only on T1 trunks that doesn’t contain the D-channel. Calls
initiated on B-channels of the Primary T1 trunk, by default, don’t contain the
Interface Identifier. Setting the parameter ISDNIBehavior_x to 2048’ forces the
inclusion of the Channel Identifier parameter also for the Primary trunk.
•
The parameter ISDNNFASInterfaceID_x = ID can define the ‘Interface ID’ for any
Primary T1 trunk, even if the T1 trunk is not a part of an NFAS group. However, to
include the Interface Identifier in Q.931 Setup/Channel Identification IE configure
ISDNIBehavior_x = 2048 in the
ini file.
21.6.2 Working with DMS-100 Switches
The DMS-100 switch requires the following NFAS Interface ID definitions:

InterfaceID #0 for the Primary trunk

InterfaceID #1 for the Backup trunk

InterfaceID #2 for a 24 B-channel T1 trunk

InterfaceID #3 for a 24 B-channel T1 trunk, and so on for subsequent T1 trunks