Filter
Top Products
2-6
NETWORK CONNECTIONS AND CONFIGURATIONS
DS1/DMI PUBLIC-NETWORK CONNECTIONS
Public-network connections may include connections to COs, DACS frames, and toll offices.
4ESS to Another System (Special-Access Connection)
Connections to a 4ESS switch are called special-access connections. The physical connection is made
directly from customer premises to the 4ESS. Toll calls go directly from a System 75, System 85,
Generic 1, or Generic 2 to the AT&T toll network.
The physical connection to a 4ESS toll switch is made (through the digital interface frame, or DIF) to
a SM9 circuit pack.
With a 4ESS, several suggestions are applicable for the special-access connection. These suggestions
and how they apply are described below.
Framing, Signaling, and Line Coding
A 4ESS provides the option of selecting either D4 or ESF framing, ZCS or B8ZS line coding, and
either robbed-bit signaling or ISDN-PRI.
E&M or Reverse-Battery Signaling
A 4ESS has been used traditionally in a class-4 or higher toll office and was not initially designed to
support lines. A 4ESS can only provide E&M and reverse-battery signaling. For DS1/DMI-BOS,
these signals are identical to E&M signaling. Therefore, all trunks (channels) terminating on a 4ESS
should be administered as either E&M or Direct Inward Dialing (DID) trunk type. (Refer to Special
Access Connections to the AT&T Communications Network for New Service Applications (326-204) for
more information.) The following options are applicable for these connections:
●
●
E&M both one-way and two-way operation; either immediate start, wink start, or delay dial
Reverse-battery — one-way incoming, either immediate start or wink start.
Dial Tone
Second dial tone may be provided by a 4ESS. However, it is recommended that a System 75, System
85, Generic 1, or Generic 2 tone plant be used to provide a second dial tone. With this arrangement,
the second dial tone can be provided through use of the Automatic Route Selection (ARS) feature on
all DS1/DMI-BOS trunks that terminate on a 4ESS.
Touch-Tone Capability
A 4ESS supports dual-tone multifrequency signaling (DTMF).