CGW-I Cellular Gateway BRI-GSM : Installation and Operation Manual
8
This diagram describes an NT1/CGW-I configuration option which can be
used when the PBX requires a single source clock and an NT1 device
connects the PSTN to the PBX. By connecting to the NT interface of the NT1
which sends the source clock to the PBX to the Synch-In interface of the
CGW, the CGW-I is able to ensure synchronization of the NT source clock it
sends to the PBX by using the source clock that the PSTN sends to the PBX.
ISDN Extension / CGW-I Synchronization
PBX
PSTN
NT
TE
NT
TE
ISDN
Terminal
Adaptor
NT
TE
Synch-In
ISDN
Phone
SIM 1
SIM 2
GSM
Operator 1
GSM
Operator 2
CGW
LCR
Source
Clock
7
5
6
12
11
10
8
4
2
1
9
3
ISDN Cable
NT
This diagram describes an ISDN Extension/CGW-I configuration option which
can be used when the PBX requires a single source clock and the PBX has an
NT interface to an extension telephone or terminal adaptor. It is common
when the communication between the PSTN and PBX is over a direct PRI
connection and there is no NT1 for synchronization. By connecting from the
ISDN cable leaving the NT interface of the PBX to the Synch-In interface of
the CGW, the CGW-I is able to ensure synchronization of the NT source
clock since it sends back the same source clock it received from the PBX.
Utilizing the existing cable also lets you avoid using additional ISDN BRI
resources (i.e., B1 or B2).
PBX Proprietary Telephone Interface with NT Card
for CGW-I Synchronization
PBX
PSTN
NT
TE
TE
NT
SIM 1
SIM 2
GSM
Operator 1
GSM
Operator 2
CGW
NT
Synch-In
NT
Proprietary Connection
Source
Clock
7
5
6
12
11
10
8
4
2
1
9
3
LCR
