Telos TWOx12 - Page 209

TELOS TWOX12 USER’S MANUAL
GLOSSARY OF TELEPHONE TERMINOLOGY
APPENDIX 4 197
S interface
- The electrical interface between the NT1 and the Terminal Adapter or
other ISDN equipment. ISDN equipment with built-in NT1’s do not necessarily
provide access to the S interface (the Zephyr, ZephyrExpress and Telos TWO do).
Multiple devices can share an NT1 by connecting on the S interface. Also known as
the S passive bus.
S0
- European term for ISDN BRI. See BRI and ISDN2.
S2M
- European term for ISDN PRI. See PRI and ISDN 30
Sealing Current
- Unlike telegraphy, teletypewriter and POTS lines, most digital lines
(such as ISDN) use a voltage rather than current mode of operation. Sealing Current
allows a controlled amount of current to be passed through a telecom circuit for
purposes of “healing” damage caused by corrosion. Bellcore specifies sealing current
on the ISDN U interface.
Silence Suppression
- See Statistical Multiplexing.
SLIC
- 1) Subscriber Line Interface Circuit, see “Line Card”. 2) The equipment used
with the AT&T (Lucent) SLCC Subscriber Loop Carrier Circuit, a system used to
multiplex a number of subscriber loops onto a single circuit to reduce fixed costs.
SPID
- Service Profile IDentifier- On the “National ISDN”, “AT&T Custom PMP” and
“Custom DMS” ISDN protocols, the Telco switch must receive correct SPID(s) from
the CPE before it will allow access to ISDN service. Intended to allow multiple
configurations on ISDN lines shared among different types of CPE equipment. While
your SPID may include your area code and telephone number, the SPID is distinct from
the telephone number. For the National ISDN, Custom PMP, and DMS custom ISDN
protocols the equipment requires that the user to program SPIDs into it. Custom PTP
and ETS 300 protocols do not require a SPID.
Station Line
– A telephone circuit from a PBX to a telephone on that PBX. Since this
is a telephone-to-switch connection it is considered to be a “line”. See Line and Trunk.
Statistical Multiplexing
- A method of improving effective bandwidth of a Telco
channel. Statistical Multiplexing takes advantage that there are typically many pauses
in a conversation. By taking advantage of this fact, and not sending the pauses,
improvements in efficiency can be made. Also referred to as silence suppression. See
circuit switched.
Switch
- Telephone switching device which “makes the connection” when you place a
call. Modern switches are specialized computers. ISDN service is provided from a
“Digital” switch, most commonly (in the USA & Canada) an AT&T model “5ESS”,
Northern Telecom model “DMS-100”, or Siemens model “EWSD”. The switch, and
related software running on it, will determine which ISDN protocol(s) will be available
to customers connected to it. See also PBX.
Switch Type
(ZephyrExpress)- The utility menu item where the ISDN Protocol is
selected. See Telco Setting and National ISDN.
Switched Circuit
- A channel which is not permanent in nature, but is connected
through a switching device of some kind. The switching device allows a switched
circuit to access many other switched circuits (the usual “dial up” type of telephone
channels). Once the connection is made however, the complete capacity of the channel
is available for use. As opposed to a dedicated circuit.