Q: What type of ISDN services does TLG support?

A: ISDN is tantalizing, but in 1994 still fraught with practical
problems. Its usefulness is still quite limited for Internet use.

There are basically three forms of ISDN you can obtain; ISDN-IS,
or plain business-rate; Centrex, ISDN-IS with off-premises
"extentions"; and residential ISDN.

ISDN-IS is billed as flat-rate of approximately $30/mo, *plus*
$0.01 per minute of connect time ($0.04 first minute), which works
out to $432.00 per month for connect time; keep in mind TLG does
not directly support non-full-time connections.

Centrex is essentially business-rate ISDN, but allows off-premises
extention lines; the same as multiple extentions on adjacent desks
within an office building, only they don't have to be in the same
building. Extention-to-extention calls are covered within the flat
rate -- there is no per-minute charge. If you had, for instance,
one extention at your site, and one at ours, you would have full-time
ISDN between your site and TLG, for the flat rate of $30/mo plus
the small monthly fee per extention.

The catch? All extentions must be within the same Pacific Bell CO
(Central Office) -- and within San Francisco, there are at least
seven CO's.  The chance of your site being within our CO is very
low. If it is however you're in luck -- contact us.

Last and somewhat least, residential ISDN now has a tarriff. It is a
split per-minute/flat-rate scheme; from 8:00am through 5:00pm it is
$0.01/minute connect charge ($0.04 first minute); all other hours
are flat rate.


If you can swim through this tangle of limitations, you may be able
to get a cost-effective connection via ISDN.


Q: What ISDN equipment do I need to connect to TLG?

A: TLG doesn't own any ISDN-specific equipment. As with modem-based
and leased-line connections, we require each member to provide the
interface between our router and the line itself; modems or DSUs,
or other equipment. (Our FAQs explain why, but basically low overhead
and low cost.)

If you are willing to provide ISDN equipment that can connect to
our system (V.35 or RS-232 interface), and can arrange ISDN service
in your own name, with a Centrex extention or ISDN-IS line at our
physical premises, we will gladly provide you with a connection to
TLG via ISDN. TLG does not install or "own" the phone lines used
to connect to us; these are installed and paid for by each member.
This lowers your cost, and our exposure to unexpected long-distance
calls, etc.

Note however we don't have provision for "part time" IP, or circuit
take-down upon idle, etc. TLG assumes you're connected 100% of the
time; if you want to use ISDN to make non-full-time connections to
the Internet via TLG, you will have to arrange for additional
support, such as MX mail forwarding. TLG can however do domain name
service for you.

Our pricing structure assumes 100% utilization; we will charge our
56K rate of $325.00/month for 64K ISDN, or $500/mo for 128K.

Q: What ISDN equipment will I need?

There are two options for connecting your equipment to TLG. The
preferred method is to use standard serial interfaces (generally
V.35 for high-speed synchronous) to our routers. The other option
is to tie directly to our Ethernet ring, which feeds all of our
routers in each POP.

ISDN/Ethernet Bridges are unusable for two reasons: one, it would
bridge all TLG traffic on the Ethernet ring to your site, both
swamping your line, and causing security problems. (Bridges are
meant to couple two LANs together, to intentionally share all
traffic on smallish networks.)