This method lets you use the same old software on your PC, just replacing the firmware in the loader phone with this new firmware. Here's the diagram:

You will have to write an EPROM and you'll have to build a cable:

Original Manufacturer's Instructions:
Types Of Phones That Can Be Programmed
We have tested the loader on as many phones as possible. It has
worked on All phones so far including the latest 94fC firmware.
It will work on Series III and IV mobile and bag units, all
PT950's, Micro-Tac Lites, Ultra Lites, pocket phones. Ultra
Classic "brick" style phones. Let us know if you come across any
firmware that can not be changed. YOU CANNOT PROGRAM "SST", TDMA
OR CDMA DIGITAL PHONES, THEY USE A COMPLETELY DIFFERENT SYSTEM.
YOU ALSO CANNOT PROGRAM 8000 SERIES BRICK PHONES.
NOTE
IF YOU HAVE NEVER USED THE MOTOROLA PROGRAMMING SOFTWARE PLEASE
FAMILIARIZE YOURSELF WITH IT FIRST.
DEFINITION
NEW PHONE: THE NEW PHONE YOU ARE PROGRAMMING.
ESN: ELECTRONIC SERIAL NUMBER.
ESN LOADER: MODIFIED TRANSCEIVER AND HANDSET.
LOADER INTERFACE: LOADER PROGRAMMING CABLE AND INTERFACE TO
DESTINATION PHONE.
DESCRIPTION
The "ESN Loader" and "Loader Interface" have been designed to
allow you to program new Motorola firmware versions. The basic
principle of operation is very simple.
STAGE 1 : Use the Loader interface to transfer the ESN
and NAM data from the new phone to the
loader.
STAGE 2: Use the "standard" programming software to
change the ESN, Phone number and other
parameters in the Loader phone.
STAGE 3: Use the Loader interface to transfer the
information back from the Loader to the
new phone.
Note: Plug test adapter into programming cable.
Check new phone software version in manual test mode
(#19#).
STAGE ONE, TRANSFERRING FROM THE NEW PHONE TO THE LOADER
The Loader interface has two female DB25 connectors and a switch,
this goes between the Loader phone and the destination phone.
Standard programming cables are used to connect the printer port
and the 12 volt ..... power supply provides power to the
interface and to the Loader phone. NOTE: Some computers do not
allow you to complete the transfer procedures with the cable
hooked to the printer port. If you have any problems complete
STAGE ONE and STAGE THREE without the computer connected. You
can experiment.
Complete steps A thru D with all power turned OFF.
A: Connect the interface to the Loader phone, an arrow on the
label shows you which is the correct connector, the switch
faces the antenna port.
B: Connect the handset to the loader phone.
C: Connect the destination phone to the Loader interface using
your standard programming cable. If you are programming
a "flip" style phone make sure you have the test mode wire
connected to the center connector on the back of the
phone.
D: Put the switch on the loader inter fetch in the TEST
position. T
E: Connect the power to the loader phone and to your
programming cable/new phone.
F: Turn the power on on the NEW phone, you will see various
numbers flash on the display.
G: Using the keypad on the NEW phone enter # 6 9 #.
H: Turn the power on on the LOADER phone.
I: Using the keypad on the LOADER phone enter # 6 6.
J: Put the switch in the PROGRAM position. P
K: Press # on the loader phone.
After a few seconds the LOADER phone should display "PASS" this
indicates a successful transfer, if you see "FAIL" check your
connections and try again.
Assuming the above was completed successfully the LOADER phone
now contains all the data from you NEW phone, continue stage two
and three. If the above was unsuccessful please see the trouble
shooting section later in the documentation. Unplug cable to new
phone.
STAGE TWO, PROGRAMMING THE LOADER PHONE
TIP: EVEREX EIGHT BIT PRINTER CARDS SEEM TO WORK BEST.
It is assumed that you are already familiar with using the
programming software, please refer to the guide that came with
your software if you need help.
A: Connect the LOADER phone to your computer using the male DB25
interface.
B: Put the switch on the loader interface in the
PROGRAM/TRANSFER position. P
C: Start your software and turn power on.
D: Use your programming software to change the required data in
the loader phone.
IF YOU HAVE PROBLEMS PROGRAMMING THE LOADER AND YOU END UP LOSING
THE ESN YOU DO NOT HAVE TO REPEAT STAGE ONE. SIMPLY TRY STAGE
TWO AGAIN.
NOTE: Unplug cable to LPT1. Plug cable back to new phone.
STAGE THREE TRANSFERRING FROM THE LOADER TO THE NEW PHONE
This is basically the reverse of STAGE one. Again you > have to
disconnect the computer while performing the transfer.
A: Put the switch on the loader interface in the TEST
position. T
B: Turn the power on on the LOADER phone, you will see various
numbers flash on the display.
C: Using the keypad on the LOADER phone enter # 6 9 #.
D: Turn the power on on the NEW phone.
E: Using the keypad on the NEW phone enter # 6 6.
F: Put the switch in the PROGRAM position. P
G: Press # on the NEW phone.
After a few seconds the NEW phone should display "PASS" this
indicates a successful transfer, if you see "FAIL" check your
connections and try again.
Assuming the above was completed successfully the NEW phone now
contains all the data from you LOADER phone. The process is now
complete.
TROUBLE SHOOTING
NEVER INTERRUPT THE TRANSFER ONCE YOU HAVE ENTERED # 6 6 #, YOU
WILL LOSE THE ESN. CLOSING THE "FLIP" ON A FLIP PHONE MAY ALSO
CAUSE THE ESN TO BE LOSE.
If you experience any problems check the following; first read
the ESN from the new phone and the loader phone, this will help
you determine at what stage the procedure failed. Connect the
phones, one at a time, to the transfer interface, put the switch
in the test position, turn the power on and enter # 3 8 #. The
phone will show the address and first byte of the hex ESN, press
the * (star) key to scroll through the ESN of 82123456 will
appear as:
00 82 (press star)
01 12 (press star)
02 34 (press star)
03 58
Turn the power off to exit test mode.
FAIL CODES:
FAIL INCORRECT SETUP, PHONES ARE NOT
COMMUNICATING
Double check your wiring, make sure your programming cable is
hooked up correctly. The cable between the loader and the new
phone must be wired as shown in the diagrams on the following
FAIL 2 NO ESN IN THE PHONE YOU ARE
TRANSFERRING FROM
IF THE PHONE HAS "1MEG: FIRMWARE ABOVE 9340 YOU CAN NOT TRANSFER
AN ESN OF 0000FFFF, CALL US, WE CAN RESET THE PHONE TO IT'S
ORIGINAL ESN.
IF THE PHONE HAS FIRMWARE BELOW 9340 TRY THE FOLLOWING:
You have an ESN of 00000000 or FFFFFFFF in the phone. Program a
valid ESN into the phone. To program a phone (FIRMWARE 9122 THRU
9339) with a valid ESN connect the phone directly to the computer
and use the old software to program it with any ESN, the phone
will not program and the software will never complete checksum
calculations. Press F10 to quit thee software while the ESN is
being written, this will leave an ESN of 0000FFFF in the new
phone. The 0000FFFF
is considered a valid ESN and will allow you to transfer. DO
NOT DO THIS IF THE PHONE HAS 9340 OR ABOVE FIRMWARE.
FAIL 9 No information available.
FAIL 11 INCOMPATIBLE PHONE
This may happen if you try and transfer FROM the LOADER to the
NEW phone without first transferring from the new phone to the
loader. IE you are using stage two and three. Try completing
stage one, if the error still happens the phone is incompatible.
FAIL 12 DEFECTIVE PHONE
This will happen when trying to transfer TO a phone that is
defective in some way, you may see this when trying to program a
phone that has corrupted firmware (display shows LOANER).
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