MOTOTRBO: The MPT1327 option board (Part 1)

To ensure a smooth migration to digital, MOTOTRBO radios are available with a MPT1327 option board. This allows you (or your customer) to use MOTOTRBO radios on their existing analogue trunked radio system while they migrate to digital.
The option board is pre-installed inside the MOTOTRBO radio and allows the radio to process the FFSK signaling and handle the channel allocations required to set up calls. In effect, the option board takes over control of the radio.
MOTOTRBO radios can be ordered with the option board pre-installed or you can install them yourself, if you have the correct tools and skills.

The option board is programmed with the MPT OB CPS, available on Motorola Online. There is also some configuration required in the host radio, this is done via the MOTOTRBO CPS, also available from Motorola Online.

In order to set up the option board, some information about the MPT system is required. There are three important parameters that will make the radio work (or not work, if you get it wrong) on a MPT system:
  • The system ID
  • The radio ID (or ident.)
  • The frequencies (channel numbers)

There are other parameters which are important, but the above three will make the radio register on the system and the user will be able to make and receive calls by dialing a number.

Sometimes the System Identity is not known or is presented in an uusual format. The best way to determine this would be to read any existing radio and copy this to the MOTOTRBO radio. Fortunately, the MOTOTRBO MPT OB CPS has the ability to open .PER (Personality) .NET (Network) and .RAD (Radio) files which were created by older versions of Motorola MPT CPS or DPS.

If your existing radios are from another manufacturer, the only way would be to print the configuration settings and create the MPTOTRBO MPT codeplug from scratch.

System Identity

The system Identity is a 15bit number continuously transmitted on the control channel (part of the CCSC). A radio will search for the control channel(s) and will look at the System Identity. If the information, in the radios codeplug, matches that which is in the decoded System Identity, and the signal strength is sufficient, the radio will attempt to register.

There are two possible bit arrangements for the System Identity:

  1. In a regional network, the first bit in the System Identity is 0. This also means that bits 2 and 8 are used for the Operator Identity (OPID) and bits 9 to 12 for Network Dependant Data (NDD).
  2. For a national network, the first bit is 1; bits 2 to 3 are used for the Operator Identity and bits 4 to 12  are for NDD.

In both cases bits 13-15 are used for the Label (LAB) sub field.

System ID bit structures for national and regional

The LAB field allows the system operator (infrastructure owner) to selectively disallow certain groups of radios access to certain sites - on a per site and even on a per control channel basis. In almost all cases, LAB is set to the "allow all" value 001 (otherwise known as control category A).

The NDD bits are also made up of some additional data: Area; Zone and Free. These three (in most cases only Area and Zone) allow a network operator (infrastructure owner) to control the roaming characteristics of radio units on a wider area basis.
NDD Example
The above table illustrates one possibility for using NDD to restrict or control site access. Each block above represents one site or multiple sites in a MPT1327 system. The number in red is just a site number for ease of reference. The Four bit (digit) number below that in black is the NDD value for that/those site(s).

In the radio, not only do we have to specificy the Area and Zone data but also the length of these. The Length of Area indicates the number of bits used to determine the area NDD value and is counted from the most significant bit to the least siginificant bit (i.e. from left to right).

It also means that in a regional network, the Length of Area (LA) and Length of Zone (LZ) values cannot be higher than 4. In a national network, LA and LZ can be as high as 12.

In the above NDD example, if we wanted to restrict a group of radio to zones 1-8, we would set LZ to 2 (meaning the first 2 bits are counted) and would add two values to the NDD Table (in the radio), namely 0 and 1. So a LZ of 2 tells the radio to look at the first two bits of the NDD (i.e. bits 9 and 10) and if these match  decimal 0 (binary 00) or decimal 1 (binary 01), the radio should continue with the registration process or, at least, add this control channel to the hunted list.

So by manipulating Area; Zone; LZ and LA, one can control who is allowed to go where in the network. If we wanted all radios to go anywhere, we would simply have the same information in all radios.

Radio Identity

In a MPT1327 network, each group and radio is allocated a unique number. This number is made up of two parts: the Fleet (NP) and the Individual (FIN).
MPT1327 allows for some customization of these numbers: here I will only discuss MPT1343.

MPT1343 allows us to split the MPT1327 number into a Prefix; Fleet and Individual number for radio units and a Prefix; Fleet and Group for talkgroups. This makes it easier for us to remember and allows users to dial understandable numbers to reach members of their team. Although different, the number used for a talkgroup and for a radio unit tie back to unique numbers in MPT1327 format.

In MPT1343 format, there are two possible lengths for the Talkgroup and Individual number. For smailler radio fleets, the Individual number can be 20-89. For larger fleets this would be 200-889. Similarly for smaller fleets, the Talkgroup number would be 90-99 or 900-998 for larger fleets.

Note that you cannot have a mixture of two and three digit Individual numbers!

  • The MPT1343 Prefix is based on the MPT1327 Prefix plus 200.
  • The MPT1343 Fleet is based on the MPT1327 Individual divided by two, then rounded to the next integer and added to 2000.
  • The MPT1343 Individual is based on the MPT1327 Individual plus 20 or 200 depending on the fleet size.

This means that a radio with a MPT1327 (base) number of 000 0001 will have a MPT1343 number of 200 2001 200. Users who want to dial this radio, and who are within the same Fleet, simply need to dial 200. Users in another fleet would need to dial 2001 200 and users with another prefix would have to dial the full number 200 2001 200.

  • For the Talkgroup number, 900 is added to the MPT1327 Prefix. 
  • 9000 is added to the MPT1327 Individual which is divided by two and rounded to the next interger. 
  • Then for the Talkgroup either 89 or 899 is added to the MPT1327 Individual.

More information about Radio Number can be found in the MPT1327 and MPT1343 standards.

The Frequencies

MPT1327 allows for two possible channel allocation methods:
  1. Standard Channel Plan
  2. Flexible Channel Plan
The standard channel plan would be used where all the RF channels in a system can be represented as a multiple in relation to a lowest common denominator frequency known as the LBBF (Lowest Baseband Frequency). The frequencies would also have to have the same TX-RX separation.
If the above does not apply, then the flexible channel plan should be used.

With the standard channel plan, the LBBF is regarded as the mathematical channel zero in the radios and system/site controller - all channel numbers are hence based on this value.

The flexible channel plan allows the system operator to define custom channel numbers and frequencies. The only require
ment is that the channel number in the infrastructure (system/site controller) matches that which the radio has.

Relationship between LBBF and Channel Numbers - Standard Channel Plan
Part 2 to follow soon....


  1. Replies
    1. Part 2 is on it's way. In the meantime, have a look at

  2. Replies
    1. Pleasure, part 2 is on it#s way. In the meantime, have a look at

  3. Thanks Wayne,
    I'm a Motorola reseler and have a customer using PRO5450 MPT's radios.
    Let me know the P/N for this MPT's option board.
    73's FR Carl,PY8MD.

    1. The EMEA part number is PMLN6996AS. The Latin America part number will be different so you would have to contact your Motorola supplier or our Customer Connect team abou this. Note that the option board will only work in the DP4000 series radios, not the PRO5450.

  4. does the MPT option board for the DP series of radios support GPS when used in analogue trunking (1327) mode?

    1. Yes. The radio has to be polled via a SDM. The GPS data is sent as a reply. The option board has to be installed in a GPS model radio of course.



  6. Hi Wayne, I enabled the Option Board in DP4801Ex. But can't read in MPT1327 GOB CPS. The Error is "Radio is not responding. Please check that the radio is powered on and connected to RIB." What should I do?

    1. Be careful about posting your email address - I get spammed regularly because my address was listed on one of the pages.

      Have you had a look at ?

      Was the radio ordered with the MPT1327 option? When the radio is put onto a OB enabled channel, does the display show some MPT1327 specific information (e.g. IDENT; hunt status etc.)

    2. Hi Wayne, we can read now using MPT CPS but in MPT mode/zone we cannot use the keypad, arrow up & arrow down button only are allowed. I was advised to upgrade the firmware using GOB upgrade kit but "unable to open file for writing" , "opening firmware file failed" after I click the program button.

      Please advise. Thanks.

    3. There is a keypad call enable option in the MPT CPS, this must be ticked. Also the dialed number must start with either a 2; 8 or 9.

    4. I have a DP4801 with MPT board fitted. Having problems with the numeric keypad. When using a contact list the numeric keypad selects the id in the contact list. e.g. Trying to dial 907 you do not get past 9 when the radio calls a number in the contact list which just happens to be 9 in the list, this happens the same with all numbers on keypad. When contact list is deselected in CPS keypad works OK, but this is not what I want.

    5. I may be wrong but that sounds like normal operation. I think you have to disable this and enable keypad call enable.

    6. Really, I would have thought you could have the option to use the "control" channel knob to select a contact as well as having the option to use the keypad as in the GP680 model.

    7. I will have to check that and get back with a more definitive answer. The DP MPT Option Board is a 100% replica of the GP series with a few added features.

      You should really be contacting Motorola Technical Support or whoever supplies you with Motorola radios with such questions - see the FAQ and SUPPORT links above.

  7. Hi Wayne,
    There is the problem with GPIO at MPT1327 OB. I have enabled option "Traffic Channel Indication Feature" as "Generic Output 1" in GOB CPS and I enabled pin 19 as "Generig Output 1" in MotoTRBO CPS. But if radio starts voice conversation (and goes to traffic channel) voltage level doesn't change.
    How can I fix this problem?

  8. What radio model is this?
    What firmware version is the radio on?
    What firmware version is the option board on?
    What is the GPIO pin set to, in the host radio?

  9. Radio model - M28QNN9KA2AN
    Radio firmware version - R02.40.10
    OB codeplug version 02.00
    OB software verstion R01.02.00
    In host radio pins 19 set to "Generic Output 1", Active level "high"
    You can download configs for OB and radio at link:

  10. The configuration seems okay.
    There are two things you could try:
    1) In MPT Personality>>Personality Options, try disabling "Use CTS OP to indicate..."
    2) Upgrade the host radio to R02.40.20 and the option board to R01.02.03.
    If the above doesn't work, please contact your Motorola dealer/supplier or Motorola technical support - see

  11. Firmware's upgrade of OB helped to resolve the problem.
    Thank you, Wayne.

  12. Hi Wayne,
    I installed MPT1327 GOB into new DP4801 by myself. I programmed 16 analog channels to radio and checked Option Board enabled . When I power on radio display shows "Model Wrong" and radio becames blocked. Could you help me to solve this problem. Thank you.

    1. Are you certain that this was the MPT option board?

      I think you can reflash the option board with the MPT OB upgrade tool if there is a version mismatch. But if this is a Connect Plus or blank GOB, you won't be able to flash it as the tool looks for a valid ESN first.

      Are you able to read the option board with the MPT OB CPS at all?

    2. O'k Wayne. The problem is in different bands of radio 300MGz and GOB 400MGz. It's a surprise that option board can restrict frequency plan of radio. May be there is a way to change GOB's band or this parameter is unchangeable?

    3. That's interesting, I've not seen that error before. The GOB CPS will allow you to edit the frequencies I think. I also remember seeing a default codeplug for 300MHz in the CPS folder but it has a strange file extension.

    4. The model of GOB printed on board is G0P0RD00JP. Does litera R match to 400MGz band? I have the only board so I cant compare with others one. And where I can get flash tool you mentioned before? I didn't see it on MOL.

    5. G0P0RD00JP is probably just a sticker they put in the factory. I checked and the same MPT OB is used on VHF and UHF when you order a radio with the MPT option - so there isn't any band dependent settings other than what goes in the codeplug.

    6. The the CPS folder there is a file called Predefine_350.cnh, try opening that.

    7. Yes, it's look like the problem is in the board settings. When I try to load Predefine_350.cnh CPS tells me "Network data is invalid". But if I try others _uhfb1 or _uhbf2 it's O'k. Is there any tool for reflashing GOB?

    8. There should be no need to reflash the option board. If you just edit the frequencies in the channel plan that should be okay.

      If you'd like to try there is an upgrade tool on Mototola Online which *might* make a difference.

    9. May be I've explained my situation not clearly. When I try to open predefine_350.cnh I see this:
      and nothing happens. If I try to modify inner configuration or predefined uhf file CPS shows the error:

    10. One thing you could try is writing a UHF1 RAD file to the radio then reading it again. The MPT OB CPS reads the host radios model number and then determines the mon-max frequencies from that. The PMLN6669 option board is used on VHF and UHF so the the operational frequency is not determined in the OB.

  13. O'k Wayne. I've done this. Thank you for help and good luck!

  14. Добрый день уважаемый!
    Проблема следующая.
    Радиостанция Motorola DP4801
    Модель платы GOB: Motorola PMLN6696
    Версия прошивки: Paradise MPT1327 gob uk r01.02.03
    GOB CPS: MPT-1327 GOB CPS R02.00.03
    после обновления firmware станции (прошивки) на версию R02.07.01.0000
    станция перестала «видеть» опциональную плату GOB MPT1327,
    по ошибке случайно плату обновили при помощи утилиты "MOTOTRBO GOB Flash" (для опциональных плат где установлен CC Connect+), вместо того чтобы использовать Paradise MPT GOB 1327 Upgrade Kit R01.02.04,
    в итоге опциональная плата не определяется, и не работает, и на дисплее появляется надпись:
    GOB 3rd party app
    Считать плату CPS не получается, и обновить тоже не получается.
    Подскажите пожалуйста, что можно сделать в данной ситуации? Может быть как то можно сделать «reset» или откат опциональной платы?



    Спасибо! Надеюсь На ваше понимание!

    1. It looks like you've flashed the option board with Connect Plus firmware. I'm not sure if you can flash MPT1327 firmware into this board now, since the upgrade tool won't upgrade a Connect Plus board.

      You might need to return this radio to Motorola for repair in Moscow (I am assuming you are in Russia or a CISFTA country).

    2. Good afternoon! Thank you very much for the answer! Tell me, please, what can I do in this case? Maybe it's easier to buy a new PMLN6696AS board? Or all the same it is possible to correct this problem?

    3. Contact Motorola and see how much the repair would cost.
      Then contact your local Motorola dealer and ask them how much a replacement option board would cost.

      I don't have a lot of knowledge about repairs so I can't help you much here.

  15. This comment has been removed by the author.

  16. Как выдумаете, можно сделать сброс GOB PMLN6696AS или откат. Может быть существует какой-нибудь дополнительный софт для GOB?


  18. Hello Wayne!
    Does radio model DP4801 EX MA support MPT1327 functionality? Can we order this model with GOB MPT1327 preinstalled?
    Thank you.


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