TUCoPS :: Phreaking Technical System Info :: 312split.txt

Technical memo on the 312/708 Chicago NPA split

Illinois Bell                                                Operations Letter
Planning & Engineering                                                CS&E 7.1

                                                              October 28, 1988

                        312 Split / New 708 Area Code

                             (Operations Forces)

1.  This letter is issued to provide information about the area
code 312 split that will occur November 11, 1988.

2.  All prefixes in the City of Chicago will keep the 312 area 
code.  All prefixes outside the physical boundaries of the city 
will become area code 708.  Customers will keep their same seven
digit telephone number.

3.  This split is necessary because customers in this fast growing
area need more telephone numbers than are now available.  The
split will be revenue neutral.  Subscribers will not pay more to
make a call that requires eleven digits (1 + Area code + 7 Digits)
than they pay for the seven digits presently dialed.  Although the
split is revenue neutral to the subscriber, it will cost Illinois 
Bell several million dollars in operating expense.

4.  A main 312 Split Committee supported by eight subcommittees
is charged with the task of implementing the split.  The split
will be accomplished with the least customer dissatisfaction
possible, without spending more expense money than needed.

5.  The Split Committee and subcommittee are identifying the
various data bases and processes affected by the split in some way.

6.  Due to Alarm Company and Carrier concerns, a "permissive"
period will begin on June 1, 1989 in some offices.  The permissive
peroid will allow either 7 or 11 digit dialing in both area code 
312 and 708.  This will allow testing by carriers and equipment
changes by the Alarm Companies.  A schedule is being assembled 
that will contain the date each office will convert to permissive
dialing.  All offices in the present 312 area will have permissive
dialing before November 11, 1989.

7.  After the split date we will continue the permissive dialing peroid
for 90 days, until February 9, 1990.  The permissive periods are
not announced to the general public.  At the end of the permissive
period a mis-dialed call will go to a special annoucement for
each area.  The permissive dialing will be in local offices only
and may not be provided outisde the present 312 area.

8.  Some codes such as 555, 591, and 976 will remain as seven digit
codes in both areas.  Mobile cellular prefixes will be a seven 
digit code in one area only and may not always be the same area
where the carriers switching machine is located.

9.  Three digit codes such as 411, 611, and 911 will all remain as
theee digit codes in each area.  A call to 411 in either area will 
provide information for both 312 and 708 areas.

10. The method of achieving permissive dialing will be different
in each type of switch.  TCN's and detailed instructions will be
issued to cover the various types of switches.  Many hours of
translations and testing are required to attain the permissive
dialing.  A computer based program has been developed to make
tests to the call-through test numbers.

11. Potential problems that may have been identified include remote
call forwarding, flexible route and automatic route lists.  In 
most cases Marketing will issue an order to make the required

12. Speed call lists, automatic dialers, computer modems and lines
that are call forwarded can also become a problem.  This is
because subscribers may forget to make the needed area code
changes.  The only known fix for this problem is extensive 
customer education.

13. Illinois Bell has begun to advertise the date and other 
information about the split to our subscribers through the media.
Bill inserts are being used to alert people about what to expect
when the split occurs.  Directories distributed late this year
will copntain references to and information about the 312 split.

14. Closer to the actual split date, the publicity will be
intensified.  This will be to alert as many people as possible
about the split and its impact.  About three.weeks before the
split, all employees will be encouraged to use the new 312 or 708 
area code whenever appropriate.  This will provide as an in service
test if any problems encountered are reported.

15. This letter is intended to be shared with all employees of the
Operations department.  Except information concerning permissive
dialing, the contents of this letter may be shared with non-
employees such as family, friends, and associates.

16. This letter will be cancelled March, 1990.

17. The oprginator of this letter is xxxxx xxxxxx, (312) 727-xxxx.

[Editor's note: Name and number of orignator omitted for lack of relevance.
 All else is verbatim from intra-company memorandum]

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