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Chapter 3 Software Configuration 27
Configuring Voice Connections
Although the TA/V.34 and TA provide access to two independent
ISDN B-channels, the COM port can control only one channel at a
time. However, once a voice connection is established, no further use of
the COM port is required for voice until the voice call is disconnected.
When you have a voice connection and the party you are
communicating with hangs up, the TA/V.34 or TA detects this and
promptly terminates the call. Thus it is possible, once you have initiated
a phone call, to send data (or a fax for the TA/V.34). The data call may
be V.110, V.120, or PPP. It cannot be ML-PPP, since ML-PPP uses
both ISDN B-channels.
Note Remember that you must give out the correct DN for handset
calls and data calls. The default for handset calls is DN2, and
the call type assignment (AT command) is
!C5=1 .
If a data call is active, a handset call may be initiated or received only
by escaping from data mode into command mode (via the
+++ escape
sequence or a software command that performs this function) before
making or receiving the handset call. Note that this will typically cause
loss of data, or in the case of a PPP session, this will interrupt the
continuity of the session and cause it to disconnect. Once the handset
connection is made, typing
ATo and pressing Enter will cause the data
connection to go back into data mode.
Note 1 If a caller attempts to call the TA/V.34 or TA voice ISDN
number while a data session is active, there will be a busy
signal. The only exception to this rule is that if you have
escaped from data mode, the call will ring. You can then
answer the call. Your data session will be inactive until you
type
ATo (and press Enter ) to return to data mode.
Note 2 When you make a handset call over ISDN while an analog
data session (modem or fax) is in progress, you will be
unable to navigate automated voice attendants.
Configuring Dial-Up Networking
You may wish to utilize the PPP and/or ML-PPP capabilities of the
TA/V.34 or TA in order to connect to an Internet Service Provider or to
remotely access a LAN. If you do this, the ISP or the administrator of