Telos ZephyrExpress - Manual (Page 181)

11-14 APPENDIX
If you find that you have the 56 kbps limit on your line, you might want to request the
Telco to upgrade the “RBOC-to-IXC tandem” circuit.
NT1s
The ISDN standard specifies two reference points, the “U” and the “S” interfaces. The U
is the single-pair bare copper from the Telco CO. A device called a “Network Termina-
tion, Type 1” converts this to the two-pair S interface.
In Europe and Asia the NT1 is always provided by the phone company, and only the S
interface may be on user equipment. ZephyrExpress units shipped outside of the USA
and Canada have the “S” interface only. In the USA and Canada the NT1 is provided by
the user and is therefore built-in to the ISDN terminal adapter.
Terminals and Terminal Types
Any equipment connected to an ISDN line is a ‘terminal’ – whether phone, computer, or
ZephyrExpress. Point-to-point lines support one terminal, while multipoint lines can
have up to eight in some applications.
“Terminal Type” is a parameter sometimes requested by the phone people. The appro-
priate value for ZephyrExpress varies depending upon protocol and is included on the
order forms.
Long Distance Carriers
Not all long distance carriers can make reliable long distance connections for ISDN. We
have found that the following work best (listed from better to worse): MCI, AT&T,
Sprint. If you have difficulties with long distance calls you should contact Telos cus-
tomer support for troubleshooting tips.
For unknown reasons, the long distance companies try to charge extra if you tell them
you are using an ISDN line. We therefore advise that you order your long distance
through your local telephone company. Tell them to “PIC” you to 288 for AT&T, 222 for
MCI, or 333 for Sprint. If the local telephone company insists that you contact the long
distance company directly, we advise that you call and just give them your phone num-
bers. Don’t mention what type of line it is.
Since we advise you not mention that the line is an ISDN line, it will be best to call the
number listed in your Yellow Pages under “Telephone Long Distance Companies” to or-
der. If you are prepared to admit that you are using ISDN (and prepared to pay a 25 to
50% surcharge) you can contact the “Switched Data Services” ordering numbers:
AT&T 800-222-0400 Business 800-222-0300 Residential
MCI Worldcom 800-727-5555 or 800-888-0800 Business 800-444-3333 Residential
Sprint 800-326-1015