Using the nRF9160 against Anritsu MT8821C In Signaling Callbox Mode

Using the nRF9160 against Anritsu MT8821C In Signaling Callbox Mode

This is a guide showing how to use the Anritsu MT8821C tester against Nordic's nRF9160.

Please use at least Cat-M version 40.10#205, NB IoT version 40.00#013 and Platform SW v40.10S#205 or later versions to have all required MT8821C implementations available when testing against the nRF9160

Setting up

The RF attenuations between the nRF9160 and MT8821C can be modified from "External Loss"

Use Nordic proprietary AT commands for selecting LTE-M1 or NB-IoT mode.



Before triggering an attach with AT+CFUN=1, you need to send AT+CFUN=4 for the detach procedure first.

The full list of AT commands supported by Nordic can be found here:

Cat-M Common settings

Cat-M Call Processing settings

NB-IoT Call Processing settings

Use SIM model number P0035 when the default Anritsu SIM card is used in "Authentication / Integrity"
Use integrity protection other than "Null" as the "Null" algorithm might not be supported in all nRF9160 builds (also in "Authentication / Integrity" selection)

Always enable "Half Duplex" functionality where selectable in Cat-M1 testing (full duplex will not work properly against nRF9160)

To enable UE to go to RRC idle mode after registration, use "RRC Release During Registration" from "RMC". This needs to be selected before starting the attach procedure.
To enable UE to go to RRC idle mode after other connections, select "use RRC state transition" from selection "General->Packet"

The selection "Inactivity Timer" in "Call Processing->Packet" keeps NB-IoT RRC connection alive until timer expires (in case there is no any data exchange ongoing).
For signaling RF testing, RRC connected mode is required (for RF related testing, it is recommended to use RMC mode from "Common->Signal->Channel Coding->RMC")

For the RSRP and RSRQ measurements being reported by nRF9160 on the own cell, select "Common->General-Scenario type 6" and EventA1 from "General->Measurement report" and enable measurement reporting from the GUI.
You can also use periodic measurements by selecting "General->Measurement->Periodical"

For the IP data application (Using Iperf and Ping from MT8821C (internally, without Control PC) can be found from "IP data"):
Cat-M1 : Set following parameters as below :
"Common->General->Scenario->Type 6"
"Common->Signal->Channel Coding->Packet"
"Call Processing->RMC->Test Mode->Off"

NB IoT :
"Common->Signal->Channel Coding->Packet"
"Call Processing->RMC->Test Mode->Off"
"Common->UL RMC->MCSIndex->"at least 4""

Options for Cat-M1 & NB IoT IP data testing :
- Cat-M1 & NB IoT IP Data Transfer SW options needed.

Taking logs

Select "menu" from UI : "Log->Save signaling log", saved *.lge log might be enough for debugging.
The *.lge file can be viewed with PA3 viewer and will help in debugging (along with the nRF9160 modem trace).

Recallable Anritsu MT8821C configuration files
- files are available on request for both M1 and NB IoT. For recalling use "Menu->Parameter Save/Recall->Recall" and select file to be recalled.

  • Hello MikeS, and thanks for the good article.

    We have an nRF9160 based IoT device in the pipeline, which should now be tested in a certified test lab. For tests, the device is programmed with MFW version 1.3.3 and AT Client sample. The person in the test lab changed the settings of the Anritsu callbox according to this article and the required AT commands were entered to the nRF9160 modem using the LTE link monitor. Despite this, the Anritsu callbox was unable to connect to the nRF9160. The nRF9160 keeps trying again, but the connection is interrupted due to an authentication error.

    Since I can't be sure what settings the test lab actually used on the Anritsu MT8821C tester, would it be possible to get a configuration file that would make sure the settings are correct?

    Best regards Iisko84

  • Hello,

    Thank you for contacting.

    If Authentication Failure is seen, it is likely because of Authentication Key K is not matching SIM card contents.
    If integrity protection is set to 'NULL' then Authentication Response message should be received correctly, but Security Mode Command is not acknowledged by the nRF9160.

    I understood that Authentication Failure is seen in this case and if attached Cat-M recallable PRM file doesn't work, could they then try whether SIM model numbers P0250 or P0260 work with their SIM card as it has different
    Authentication Key K?

    Best regards,


  • Hello again MikeS,

    The test lab employee just messaged me that they can't find that version (40.105#206 or 40.10#205 ) on Anritsu's website and that Anritsu's website claims that the FW version (40.10#076) they are using is the latest. Is that particular Anritsu FW version available somewhere else?

    He also told about those SIM model numbers that they are using the same in both mode.

    Best regards,


  • Hi,

    According to Anritsu this FW 40.105#206 (which contains all the fixes required for nRF9160) is not yet officially released, but Anritsu can provide this latest Cat-M1 FW to you. Can you please contact [email protected] as they are aware of this request?



  • Hi,

    And thanks again for the quick reply. The test laboratory has now contacted Anritsu and asked about the firmware in question. I'll let you know when we get to try it.

    Best regards


  • Hello,

    I just came to let you know that now everything seems to be working between Anritsu and nRF9160.  

    Anritsu's customer support provided the latest Cat-M1 FW (40.105#206 ) to the test lab very quickly, but we didn't get to try it right away.

    However, that Anritsu's configuration file ( you shared earlier didn't work even with the latest FW. Anrtisu announced again "illegal file" when they tried to recall the file to the Anritsu. However, this doesn't matter anymore.

    And I have to admit that the instructions in this article are up to date and correct. We should have just immediately trusted the note at the beginning of the article and requests the latest FW version from Anritsu.. Thanks for your patience and Merry Christmas!

    Best regards


  • Hello, 

    Very nice to hear that nRF9160 is now working correctly against Anritsu MT8821C in your test lab.

    I will check why might not work as it should.

    Merry Christmas!

    Best regards,


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