Advertisement
set is used for call set-up then the modem is connected to the line after the connection has
been established.
A number of important points should be remembered to enable a modem-modem connection
to be established:
-
A modem can be connected to any type of ALC.
-
The ALC to which the modem is connected must be allocated a DNR.
-
The destination DNR must be included in the appropriate dialling tree of the calling party.
-
The traffic class of the calling party must at least have the same traffic class as the
destination number indicated in the dialling tree.
-
The IBSC 14=`SOPHO speech' should be allocated to the DNR.
-
The BSPT 14=`SOPHO speech' (or another voice BSPT) should be allocated to the DNR.
-
The CV of the DNR must be created as voice (CRCVAL or CHCVAL) and assigned to the
DNR (CHAGCV).
-
The compatibility value connection allowance between the CV of the calling and the CV
of the called party must be set to allowed (CHCVCA). For more information: see
Appendix A.
-
No facility class mark inhibits the connection.
-
The facilities offered by `data protection' prevent a break-in attempt by another extension
or operator. A break-in to an established modem connection could disturb the data
connection.
For more information on these mechanisms: see Facility Implementation Manual;
Management.
2.2.
CONNECTING A DTE TO A DLC/DTX
A DTE can be connected to the ISPBX using a Digital Line Circuit (DLC) or Digital Trunk and
Extension (DTX) board and a DCE. The DCE is a SOPHO-SET, SOPHO-LAM or LAM.
The DLC-A, B, C, D or U is connected to a SOPHO-SET, LAM or PNT1 using a 2 wire, 2B+D
S
interface connection. This is a twisted pair connection over which two user (2B) channels
0
of 64 kbps and a signalling (D) channel of 16 kbps are transferred. An additional 8 kbps
synchronisation signal, makes the transmission speed 152 kbps. Existing twisted pairs (a-b
wires, as used for analogue telephones) can be used for these data connections; no new wiring
needs to be installed. The imperfections of the line are compensated for by using echo
cancelling techniques for the transfer of digital information.
The DLC-I or DTX-I is connected to a SOPHO-SET or SOPHO-LAM using a 4 wire, ISDN
2B+D S{inf0} interface connection.
9
Advertisement
