TELECOM Digest OnLine - Sorted: Re: Enterprise and Zenith Numbers

Re: Enterprise and Zenith Numbers

Mike Z (
Wed, 09 May 2007 06:51:21 +0000

PAT: Please do NOT display my email address!

Patrick Townson wrote:

> If I am not mistaken -- but my memory is getting so awful these
> days -- 'Enterprise' was the name for Bell System subscribers and
> 'Zenith' was the name for GTE/other subscribers when used to
> _originate_ auto-collect calls (although subscribers could and did
> call any number even if on some other telco.) In other words, a
> national firm using that service might have both an Enterrise number
> and a Zenith number, depending on _which_ subscribers (by telco
> territory) were calling them.

No. And this has been discussed in the past in this forum as well.
Both Zenith and Enterprise numbers could terminate to either Bell or
non-Bell numbers, and both Bell and non-Bell customers could originate
a call to both Zenith and Enterprise numbers. Remember that AT&T Long
Lines ran the whole "show" as well. The non-Bell independent telcos
simply "played along" with whatever AT&T (Bell) implemented.

It's possible that "legacy" Enterprise numbers were still in use in
certain parts of the US, but both were in use, and they were (are) NOT
any indication of Bell vs. Independent. Zenith numbers (I'm not sure
about Enterprise numbers) have been in use in Canada as well, and
remember that Bell Canada was also once part of AT&T's corporate "Bell

Back in the 1920s and 30s, when toll service really began to be used
more than in the past, AT&T/Bell and the independents tagging along,
came up with this "reverse charge" service where the operator didn't
need to actually announce a "collect call". Some of the earlist
numbers were called "Commerce". Later they began to use "Enterprise".
Quite possibly, since some customers might have actually tried to
"dial" to CO (26) or EN (36), especially where there might have been
numbers beginning 26 or 36, or with real (dialable) EXchange names
corresponding to those digits, is when the use of Zenith came about.
Most dials don't have a 'Z' on them, although now-a-days you will find
dials with a 'Q' along with P/R/S on the '7', and a 'Z' along with
W/X/Y on the '9'. But there were some dials in the old days which had
a 'Z' on the '0'. Since Zenith numbers HAVE to go through the Operator
any customer thinking that they can dial ZE followed by the three,
four, or five remaining digits will reach an Operator when trying to
dial a 'Z' on the 'zero'.

There were also 'WX' numbers in use in some places which were the same
as Zenith and Enterprise, and earlier Commerce numbers. Since there
probably weren't that many '99' numbers, even though 'WY' can be used
to form and EXchange name, many places used the underused or non-used
99 for "real" telephone numbers, for 'WX' pseudo numbers for this
manual reverse-charge service.

But NO, it is NOT true that "Zenith was GTE/independent and Enterprise
was Bell". All telcos throughout the US and Canada could use both.

Also, regarding Operator Codes, such as 141 for Rate and Route:

> Do you happen to know or remember what the various 'operator codes'
> were for various functions? Such as inward, I think was '121', if
> your operator had to reach a 'ring-down' point I think it was
> '181', and as you stated above, rate and route was 141. Do you
> recall all those codes?

Yes, I most certainly do.

And there was '131' for reaching distant Directory or Information.
There was also '101' for reaching a test board. And there were several
11XX(X) codes for reaching all other kinds of operators, usually of
the form 115X(1). These were "mostly" universal in use throughout the
US and Canada, but there would always be some exceptions as well.

As for 181 for Ringdown, over time, there wouldn't really be any
dedicated 181 Ringdown operator, and the originating operator would
simply reach the 121 Inward operator in the distant point for
assistance in reaching any kind of non dialable destination. It's
possible that 181 would also work and reach "inward" since the
traditional use of 181 was to reach the dedicated Ringdown operator,
but in the 1980s and 90s, most operator instructions stated 121 Inward
for assistance in reaching distant ringdowns.

In all of these codes, the area code and 0XX toll center code would be
keyed where needed, before the 1XX Operator Code.

Other than 101 Test Board, 121 Inward, and 131 Directory, I really
don't know how many other of these codes are still used today in their
traditional sense by the incumbent telco industry throughout North
America, i.e. the Bells, incumbent independents, AT&T Long Distance.

[TELECOM Digest Editor's Note: Thanks very much for this detailed
explanation. Do you also remember 'Operator 7' for the occassions
when a subscriber placed a person to person call and the called party
was unavailable? Operator would tell whomever took the message to
'leave word for (person) to call (wherever) and ask for Operator 7
to return the call to (number)? That was a signal to tell originating
telco the returned call had actually been originated from the other
end as person to person and to treat the call (and bill for it) that
way? It also served as a signal for the answering party (who was
really the person requested, but he had lied about it) to call back
direct dial station rates to his party. PAT]

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