TELECOM Digest OnLine - Sorted: Re: Private Line History

Re: Private Line History

Bill (
Sat, 07 Jul 2007 03:10:28 GMT

In the late 70's until the 1984 break up I worked at the NY7P AT&T
Private Line office located at 811 Tenth Avenue, Manhattan. N7 PL was
a conventional private line office that provided both switched and
non- switched voice, as well as voiceband data. Digital Data (DDS) was
offered by the NY7D DDS office on the eighth floor. I was slated to
work at the CCSA#5 office in 1979, but at the last minute I was
swapped with a guy that was a former WECo installer that had been laid
off in 1974. CCSA#5 at the time was only a few lines drawn on the CO
floor that signified where the equipment frames were to have been
placed. The feeling was that the former WECo employee would give added
benefit to the new office since he had worked on some 1ESS
installations in the past. In the long run that swap did me a great
favour, because I may have never ended up at NYT, and survive to see
thirty years of service. Compared to my former AT&T coleages who saw
many lay offs at AT&T beginning in the 1990's.

There were two CCSA offices operating at the time CCSA#4 & CCSA#5. Both
CCSA offices were equipped with four wire #1A ESS switches that carried
private switched voice services under what was know as Feature pacgake 14
(FP14) services. As compared to FP12 which was limited to PBX/Centrex to
PBX/Centrex inter-tandem tie trunk groups. CCSA #6 was also a #1A ESS
that went in on the third floor over the mobile telephone garage area of
the building, adjacent to where 5450T, a #4ESS , was later installed to
replace the NY7 #4XB (Card reader), and latter NY6, a #4XB ETS. Both NY6
& NY7 were retired and were ripped out by late 1983.

The #1A ESS machines were predated by #5XB's that had been already been
retired and were being removed about the time I started working at NY7P.
Interesting fact. In the early 1970's the old NY7 wideband data group,
which eventually became the DDS group, was responsible for maintenance
operations of the CCSA #5XB equipment. In fact the old CCSA 17B boards
survived past divestiture and bacme the property of NY Telephone when the
NY7 DDS HUB was transferred to NYT as a result of divestiture. The test
boards were not in voice operation, but functioned on a limited capacity
to support some DDS related traffic in the NY7D office on the 8th floor.

One story from an old friend of mine, who works as a carrier
technician at the nearby Verizon W50 Street CO, mentioned that some
one in the Wideband /CCSA office had once amended a recorded
announcement on a GE network that included the following at the end of
the network voice announcment; "and you can be shure if it's
Westinghouse." Needless to say, the appended message on the GE CCSA
network did not last very long.

Many of AT&T's CCSA customers in the mid 1980's used non-AT&T LD
connecting facilities (MCI, SBS, US Transmission Systems) between CCSA
offices. AT&T would supply a 2600Hz SF signaling unit at each AT&T
end, and then connect strictly at the VF to the OCC carrier taking the
trunk circuit to a far end city location. Most Off Net Access Lines
(ONAL's) were local (POTS) ground start trunks. In some instances, the
serving CCSA office might provide a loop start FX like connection to a
telephone set, typically a key system, where users may not have had a
local PBX to switch traffic.

I recall from speaking to a few folks who I knew, and who were still
working at AT&T in the late 1980's that there was a plan to replace
the 1A's with 5E's. I recall handling GSA E&M trunk circuit troubles
that originated at 811 Tenth Avenue CCSA offices via a T1 handoff
between NYT & AT&T. The T1 interface was a significant change from the
traditional eight wire Type 2 E&M metallic circuit interfaces that had
been previously used by AT&T on access circuits at the 811 POP.

To clarify a point about CCSA & the 1960's. the first #4ESS that went
into message service was the Chicago 7 office in 1976. Since I left
AT&T on January 1 1984, I don't know the time lines for the CCSA 1A
retirtments, definitely well short of a 40 year replacement cycle, but
with the introduction of SDN, and non hierarchal switching in the AT&T
LD network, I suspect any migration of CCSA networks to 4ESS equipment
must have occured in the early 1990's, in concert with AT&T's retirement
of analog long haul FDM carrier facilites.

NY7 PL Alumnus wrote in

> Charles Gray wrote:

>> In retrospect, the CCSA was a predecessor to the "software defined
>> network" that was introduced by AT&T, Sprint and MCI in the late
>> 1980s.

> Once again, thanks for your excellent and accurate description.

>> I don't know for sure, but I expect the switches were the Western
>> Electric 4E tandems.

> Here's an extract from the Bell System history:

> CCSA -- Common Control Switching Arrangement

> "Growth in public switching was paralleled by expansion of private
> line services, and, as might be expected, this required special
> services and featurs. In particular, arrangements were developed for
> No. 5 crossbar and No. 1 ESS so that the central office provided not
> only Centrex service for one or more customers but acted in nationwide
> two-level hierarchical private networks that served the
> telecommunication needs of large businesses. By dialing an access
> code, usually 8, the customer's employees could reach company or
> agency locations on the network. In order for the switching offices
> to be shared by several private networks, common-control switching was
> required, hence the name CCSA. A special 4-wire version of the No. 5
> crossbar system was developed in 1960 to serve as the first or higher-
> level (tandem) in these networks."

> "In many cases, CCSA networks include not only PBXs but also Centrex
> service from the same switching systems. CCSA service includes not
> only access to private network switching and transmission facilities,
> but also local and distant (foreign exchange) access to public network
> and dial or tie trunk facilities between PBXs connected to the
> network."

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