MacTerminal should be used as a troubleshooting procedure to determine why a dial-up connection cannot be established.
Once dialling and handshaking is complete, you should be prompted for username and password. Specify the relevant details, pressing Return after each. If successful, the terminal window should disappear and return you to the main Remote Access window which will show that you are connected.
If you have reached the point where the main Remote Access window reports that you are connected (with the blue and green light blipping away), then it is likely that the problem lies with the modem script you were previously using when trying to connect. Disconnect, turn the terminal options off and try to connect using an alternative modem script. If you are unable to connect with any other modem script, but MacTerminal still works successfully, then you may consider saving your own modem script for Remote Access to use in future connection attempts. To do this:
Future connection attempts should now be handled via the custom modem script that was generated by MacTerminal.
If MacTerminal fails to authenticate, then the problem is almost certain to be due to a problem with the account in SABS (check the testbed if you haven't done so already) or because of a misspelling by the customer. The chances of a software corruption causing an authentication failures at this point is almost nil.
No dial tone errors in MacTerminal are exactly what they claim to be - check that the physical connections are sound and that there are no problems with the analogue phone line being used to try the connection.
No carrier errors in MacTerminal are usually signs that the handshake has taken too long and has effectively timed out. Make sure that the correct POP number is being dialled (perhaps try atdt 123 to make sure that the modem can dial into the Speaking Clock) and try again. Because the MacTerminal test does not make use of any modem script (hence the selection of Null Modem in the Modem control panel), a faulty modem script should not be the reason for a no carrier error at this point. The error often points towards getting the modem cable and/or phone line checked out. It may be the case that some modems just need a correct initialisation string to be specified in order for them to connect successfully, though the failed use of the ATZ command you issued earlier means that this is unlikely. If the no carrier error is occurring constantly, the customer will need to contact their modem vendor and/or telco for a suitable resolution.
Although MacTerminal doesn't report many error messages, there may be other reasons apart from those mentioned above as to why a connection cannot be established. If the physical connections and hardware appears to be fine, the account works on the testbed and the customer appears to be entering the correct username and password, then there may be some other software issue causing a problem. The most likely of these is a corruption in some component of Apple Remote Access and/or Open Transport, in which case reinstalling the relevant components from the OS CD may resolve the problem. Try to consider everything else before reaching the conclusion that a reinstallation is in order. If that fails, you're left with no other choice but to RTV.
NOTE: The above processes can also be carried out on Macs that use PPP instead of Remote Access.