Hayes Microcomputer Products DIVA T/A ISDN - Manual (Page 98)

DIVA T/A ISDN Modem User’s Guide 98
Analog Device Support
(Only available on some models)
The DIVA T/A has two analog device ports that let you connect
analog devices such as ordinary telephones, answering machines, fax
machines, and modems. Calls to and from these analog devices are
carried over your ISDN line. You also get additional calling features
such as Call Forwarding etc. For more information on these calling
features see page 100.
Since ISDN uses two B-channels, the DIVA T/A can support up to 2
concurrent analog device connections (depending on whether there is
a data call in place or not).
Whenever possible, you should use Multilink PPP (MLPPP) since it
provides maximum throughput with the remote device. You can also
use PPP, V120 or V110 protocols. In these cases, one B-channel is
always available for voice.
Multilink PPP without AO/DI support
In the case of Multilink PPP, one analog device can still be used if
Dynamic Bandwidth Allocation (DBA) is enabled.
For example, while a MLPPP data connection is in progress, one of
your telephones rings. As soon as the phone rings, the MLPPP
connection automatically drops one of the B-channels, reducing the
data connection from 128 kbps to 64 kbps, and the voice call is then
connected. After hanging up the voice call, the data connection re-
establishes the second B-channel and brings the data connection back
up to 128 kbps. The same holds true if you decide to pick up the
phone for an outgoing call.
While a data connection is in progress, only one voice connection can
be established to retain the data connection.
To use DBA, verify that Dynamic Bandwidth Allocation (DBA) is
enabled using the Windows Configuration Tool, or the VT100
Configuration Tool.
Two Voice Calls
When both B-channels are used for voice calls, data calls are not
allowed. The user is responsible for any new attempt at placing a data
call.