EC25-au (brazil) LTE not sucess call over LTE (VoLTE)

I have sucess call over 2G and 3g But no have sucess with VoLTE , with this under procedute (i create reading documentation)

Need Update Firmware ???


#seguencia de pesquisa de sinal : (e.g.: 04030201(LTE/WCDMA/TD-SCDMA/GSM))


#preferencia de procura de sinal (0 auto , 3 LTE , 2 wcdma)

AT+QCFG=“nwscanmode”,3,1 # somente trocando o 3 por 2 funciona ligação

AT+CGREG? ////Get the registration status of the device. If the status is ‘1’, the device is registered and in home network
#pergunta se a voz est habilitada
#habilita voz
AT+QGPSCFG=“outport”,“none” (desabilita o gps para liberar a porta para voz)
AT+QPCMV=1,0 (som na proxima interface depois da interface AT , similar ao huawei)

#desliga a ligação

Dear Sir,
Normally, please follow up the following AT command sequence to test VOLTE. Thanks!

h. AT+QNVRF="/nv/item_files/modem/mmode/voice_domain_pref"
i. AT+QNVFR="/nv/item_files/modem/mmode/sms_domain_pref"
j. ATI

You can use AT+COPS? to check whether the module still can register on LTE, if yes, then the VOLTE test is ok, if not, maybe the SIM card can not support VOLTE or the module need to do some setting which need to catch module’s debug log to confirm. You can contact our local FAE or send email to to get support on site. Thanks!

UPDATE : after i set to all frequences , connected to Network “TIM”


  • AT+QCFG=“band”,53,7FF,0
  • OK
  • +QPCMV: 1,2
  • OK
  • AT+CPIN?
  • OK
  • AT+QCFG=“band”
  • +QCFG: “band”,0x53,0x7ff,0x0
  • OK
  • AT+QCFG=“nwscanseq”
  • +QCFG: “nwscanseq”,0405030201
  • OK
  • AT+QCFG=“nwscanmode”
  • +QCFG: “nwscanmode”,3
  • OK
  • AT+QCFG=“nwscanmode”,3,1
  • OK
  • At+CREG?
  • +CREG: 0,1
  • OK
  • AT+COPS?
  • +COPS: 0,0,“TIM TIM”,7
  • OK
  • +CGREG: 0,1
  • OK
  • +QNWINFO: “FDD LTE”,“72403”,“LTE BAND 1”,50
  • OK
  • ATD10315;
    **** NOT DIAL …

Dear Sir,
Please contact our local FAE in Brazil, if you do not know the contacts, please send email to They will help you debug VOLTE . Thanks!

Yes no have Generic VoLTE in my module …


+QMBNCFG: “List”,0,0,0,“ROW_Generic_3GPP”,0x05010824,201806201
+QMBNCFG: “List”,1,0,0,“TW_Mobile_China_VoLTE”,0x05800301,201805021
+QMBNCFG: “List”,2,0,0,“Bouygues_France_VoLTE”,0x05800101,201705111
+QMBNCFG: “List”,3,0,0,“VF_Germany_VoLTE”,0x05010415,201705111
+QMBNCFG: “List”,4,0,0,“Reliance_India_VoLTE”,0x05800204,201712141
+QMBNCFG: “List”,5,0,0,“Commercial-Smartfren”,0x05012509,201801081
+QMBNCFG: “List”,6,0,0,“Telstra-Commercial_VoLTE”,0x05800713,201803091


1 Like

After i receive from suporte quectel update for TIM Brasil (file mbn) and sucess to update .

Now is possíble i try calls


[2019-10-27_20:17:36:942]+QMBNCFG: “List”,0,0,0,“Reliance_India_VoLTE”,0x05800204,201712141
[2019-10-27_20:17:36:942]+QMBNCFG: “List”,1,0,0,“TW_Mobile_China_VoLTE”,0x05800301,201801301
[2019-10-27_20:17:36:942]+QMBNCFG: “List”,2,0,0,“Bouygues_France_VoLTE”,0x05800101,201705111
[2019-10-27_20:17:36:942]+QMBNCFG: “List”,3,0,0,“VF_Germany_VoLTE”,0x05010415,201705111
[2019-10-27_20:17:36:962]+QMBNCFG: “List”,4,0,0,“Commercial-Smartfren”,0x05012509,201801081
[2019-10-27_20:17:36:962]+QMBNCFG: “List”,5,0,0,“Telstra-Commercial_VoLTE”,0x05800713,201803091
[2019-10-27_20:17:36:962]+QMBNCFG: “List”,6,0,0,“ROW_Generic_3GPP”,0x05010824,201806201
[2019-10-27_20:17:36:962]+QMBNCFG: “List”,7,0,0,“TIM_Brasil_VoLTE”,0x05800B02,201806061


Dear Sir,
How about your VOLTE test now ? Whether you can make a VOLTE call successful ?
Just as you have said that you have update the MBN file successful which can support TIM Brasil, then you can follow up the test step that we provided to have a try. If still failed, please provided your test AT log and also the debug log. We will help to debug it. Thanks!
By the way, you also can contact our local FAE or send email to to get support on site. Thanks!

Hi yes i have (i need update for more other operators , claro , vivo , oi , and more ) .

In this moment i try using virtual interface audio “AT+QPCMV=1,2” , but i have issues with mic .

I try create my code to fix this , but in this moment is in alpha my code.

Dear Carlos,
Could you tell me why you will use the command AT+QPCMV, which is different application from VOLTE, right ?
As we know that AT+QPCMV is used to enable to transfer PCM Data via USB or UART Port. Thanks!
And about your issue with MIC, could you share more information with me, then we will try to help you to solve it. Thanks!

Frist :

Second :

Tree : ( Quectel_EC2x&EG9x_Voice_Over_USB_and_UAC_Application_Note_V1.0.pdf )

For this i have problem with mic.

Dear Carlos,
Could you describe your issue in detail ? As you know that Voice over USB and UAC are different, and they are all verified.
If you test Voice over USB function, you can try to follow up the following steps to have a try. Thanks!

  1. AT+QGPSCFG=“outport”,“none”
  2. AT+QPCMV=1,0
  4. ATD dials a call or ATA accept the incoming call on the USB AT port.
  5. PCM application on the device will receive 640 bytes of PCM data through USB NMEA port in every 40ms, and process the received data immediately (broadcast or save).
  6. PCM application on the device will obtain MIC recording data through audio process unite. It is required that the PCM application should send 1600 bytes of voice data to USN NMEA port at an interval of 100ms.
  7. Execute ATH command to hang up the phone on the USB AT port or the opposite side hangs up the call, and USB NMEA port will stop outputting PCM data.
  8. Execute AT+QPCMV=0 to disable Voice over USB functionality on the USB AT port.

Yes i know , in frist moment i try use my application to use ec25 UAC , over “alsa/pulseaudio” .

My other code for use with python to create a dashboard for calls , i use USB NMEA , this is next change i need in my code , but in this case is more complex , to create from scratch.

Thanks share specs for use port USB NMEA , you gave me more information than I had separated , big thanks .

After i have success , i share my project over licence GPL in github and in this page too .

Dear Carlos,
Thanks, we will waiting for your news. Any help you need, please do not hesitate to contact us. Thanks!

My code for reference :
Is not finished , but is probable work partial

Thanks for your sharing. Thanks!

Hi i test with my software, i receive audio, but my mic is not send to other side.
I test with windows and have same problem with Qnavigator_V1.6.9.1.

Is there any other parameter that I may have missed?

Dear Carlos,
If you can receive the audio, the module uplink is normal, and about your MIC, it is better to check whether the hardware design have any problem.
And the module have no any other special parameters setting, you can check the following document. Thanks!
Quectel_WCDMA&LTE_Audio_Design_Note_V1.2_20170723.pdf (1.5 MB)

I understand that I must check my hardware.

My question is if the modem supports audio on both sides and if so, what configuration do I need to adjust by serial AT command, to activate the sound on both sides of the connection.

Edit :

I Read this pdf (big thanks) , and i found this sequence :


I not sure if is this option i need configure to receive both side (with NMEA ou UAC) , is possible inform if is this i need to receive both side ? (for me I haven’t fully understood it yet.)

Dear Carlos,
Yes, the module can support audio on both sides. Normally, you do not need to set any special parameters, just need to pay attention to use the right audio path like handset or speaker, of course you should need to connect the external codec chip set. Just the above need to be noted. Thanks!


NB: I have posted the same question here which I hope is OK: /asterisk-volte-support/5232)

Hello Carlos, Kyson,

If this was resolved please could the solution be summarised and published here.

If possible I wish to achieve the following:

Summary: Analog phone FXS calls over VoLTE with Quectel EC25, EP06 and >Cat6 modems

Equipment Bill of Materials

Is this feasible and likely to be successful?

I look forward to hearing from you.

Many thanks,