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MultiModemISDN User Guide
•No terminal adapter at the other end.
•A faulty communications device, computer, or software at the other end.
•Incompatibility between communications devices.
•An improperly configured MTA128ST-USB.
Narrow the list of possibilities by using extended result codes. To enable them, enter ATV1X2 and
press ENTER while in terminal mode or include V1X2 in the MTA128ST-USB’s initialization string
(V1X2 is enabled by default). When you dial again, the MTA128ST-USB reports the call’s progress.
•If the MTA128ST-USB reports
NO DIALTONE
, check that the ISDN S/T cable is securely
connected to both the unit’s ISDN jack (not the AUX jack) and the ISDN network terminator
or wall jack. If the cable looks secure, try replacing it. If that doesn’t work, the problem may
be in your building’s telephone installation. Make sure ISDN cables on all devices are wired
straight-through (pin 1 to pin 1, pin 2 to pin 2, etc.) and do not have reversed pairs. The cable
must have at least the middle four pins (pins 2, 3, 4, and 5) connected. A reversed pair on the
U (phone company) side is not important, but a reversed pair on the S/T (your) side can
create problems if you have more than one device, since multiple devices attached to the S/T
interface must all have the same polarity.
•If the MTA128ST-USB reports
BUSY
, the other number may be busy, in which case you
should try again later.
•If the MTA128ST-USB reports
NO CARRIER
, no connection was made. You might have dialed
the correct number but the other computer or software was turned off or faulty. Check the
number and try again, or try calling another system to make sure your unit is working. Also,
check that you accurately configured the TA with the correct switch type, TEIs, data protocols,
and other parameters needed for a successful call (see Chapter 3).
You can place data calls but not voice calls or vice versa•You might not have ordered both voice and data service from your ISDN provider. Check your
contract or latest statement of service from your ISDN provider.
•Your ISDN provider may have programmed the switch incorrectly. Call the provider.
You cannot place two simultaneous data calls•You may not have ordered an ISDN line configuration that supports two simultaneous calls.
Check your contract or latest statement of service from your ISDN provider. Also, your ISDN
provider may have programmed the switch incorrectly. Call the provider.
•You may have misconfigured your MTA128ST-USB to dial two simultaneous data calls. The
command AT&J1&W0<cr> is used to indicate whether outgoing calls should be made on two
B-channels by default.
•You may be using the wrong
bundling
dial modifier (e.g., ATD7853500&7853502<cr>). The
ampersand in this command string is correct. Other valid characters joining two telephone
numbers include a plus sign (+) and an exclamation mark (!).
Note: In Windows 2000 and Windows 98/95, if the Use Country Code and Area Code box is checked in
the Properties window for dial-up connection, the bundling modifier (i.e., &, + or !) is removed from
the dialing string when the user attempts to make a connection. The solution is not to check the Use
Country Code and Area Code box or to simply add the bundling dial modifier to the phone number at
the time of connection.