AudioCodes Mediant 800 MSBG - NFAS Interface ID

SIP User's Manual 644 Document #: LTRT-12804
Mediant 800 MSBG
10.4.1 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.
10.4.2 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
For example, if four T1 trunks on a device are configured as a single NFAS group with
Primary and Backup T1 trunks that is used with a DMS-100 switch, the following
parameters should be used:
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 ;B-Channel NFAS trunk
DchConfig_3 = 2 ;B-channel NFAS trunk