48
Chapter 6
Depending upon the location you are dialing, there may be an
incompatible local or toll telephone company. Though this is
uncommon, if you suspect a telephone company problem
when dialing local or toll data connections, contact your local
telephone company and have it verify that you can dial a data
call to the destination telephone number.
3.
Make sure that the local and remote data applications have
communication capability and are properly configured. Once
you have verified that communication capability exists, make
sure that the B-channel call data rate is the same as the
remote destination B-channel call data rate.
If you are able to establish a data connection (in which the B-
channel LED remains lit and your communications application
receives a CONNECT message), but you are unable to send
data, then it is possible that:
■
There is a difference in the local and remote B-channel
data rates. Check with your telephone company.
■
There is a mismatch in the data communications proto-
cols (such as V.120 versus PPP). Check with your network
administrator or Internet Ser vice Provider (ISP).
■
There is an interoperability mismatch between the local
and remote applications. Check with your network admin-
istrator or ISP.
4.
From a terminal emulation program, use the AT>VD com-
mand to test your ISDN connection. If your client software
cannot establish a call, you may be able to use the CCIT
cause codes returned by the ISDN switch to identify cer tain
problems. Look for the line that reads “- last call attempt:
CCITT failure cause = 0x10”. You can interpret the code as
follows:
■
0x01 - Unallocated/Unassigned Number. While the num-
ber is in a valid format it is not currently assigned. This
may be an indication that you have a wrong number. You
may also get this code if you tr y to establish an ISDN con-
nection using only a seven-digit phone number when the
full eleven digits are required. Check with your telephone
company to see how many digits to use. Also, see code
0x58 below.
