EC25 (EC25-EUX) and UAC + VoLTE

IoT Modules LTE Standard Module
1

Hi Experts!

I’ve seen a topic on similar model, EG25 and 16kHz sample rate: EG25 16khz Sample Rate UAC Audio Mode - #6 by buda.
Is there any plan to release a firmware update which supports better audio quality over USB? Based on the application notes, I see that UAC is the only option for EC25:

image
image774×132 25.9 KB

For reference, I’m currently running firmware EC25EUXGAR08A19M1.

2

Dear @omik ,

Good Day to you,

I have checked the Release Notes of the latest version which is EC25EUXGAR08A19M1G_A0.303.A0.303 and has the update on the improved UAC and other audio functionalities:
image

In order to provide the latest firmware, kindly send me the information below:
A) Your module full firmware version(use AT command: AT+QGMR)
B) What is the constant issue of audio quality that you are facing, is the audio not clear? etc.

Thank You and have a Great Day Ahead!

3

Dear Quectel Support Team,

I am writing as a user of Quectel EC25-EUX module in Europe (Poland). My current firmware version is EC25EUXGAR08A13M1G_20.200.20.200 (verified via AT+QGMR).

I am experiencing poor VoLTE audio quality issues (low volume, distortion during calls). From forums and release notes, newer versions like EC25EUXGAR08A19M1G_A0.302.A0.302 or A0.303.A0.303 include VoLTE optimizations and stability improvements.

Could you please provide:

  1. The latest official firmware package for EC25-EUX (compatible with my version).
  2. QFlash tool and update instructions (DFOTA or USB).
  3. Release notes confirming VoLTE audio enhancements.

Module details:

  • Model: EC25-EUX
  • Current FW: EC25EUXGAR08A13M1G_20.200.20.200

Thank you for your assistance. I look forward to your response.

Best regards,
Grzegorz
grzegorzgbp@gmail.com

4

Hello @Alvin295337,

Thank you for your quick reply! Here are the answers for your questions:

AT+QGMR
EC25EUXGAR08A19M1G_A0.302.A0.302

In LTE + VoLTE scenario (IMS registered, no 2G/3G fallback) the audio quality over UAC is worse compared to the usual VoLTE calls – I can understand the caller, there’s no noise, but the overall sound feels like an older, low-bandwidth analog phone in a phone booth.

To make sure I’m using VoLTE I did the following test:

  • check if IMS, LTE and VoLTE are enabled
  • check AT+CREG on idle
  • call the device from another phone
  • answer the call
  • check AT+CREG once again if there’s CS fallback

The results look like I’m indeed using VoLTE call:

AT+QCFG="amrcodec"
+QCFG: "amrcodec",63

AT+QCFG="ims"
+QCFG: "ims",1,1

AT+QCFG="volte_disable"
+QCFG: "volte_disable",0

Then the call test:

AT+CREG?
+CREG: 2,1,"E183","<REDACTED>",7   <------ LTE mode

OK

RING <------ called from another mobile

^DSCI: 3,1,4,0,<REDACTED>,145

+QIND: "ccinfo",3,1,4,0,0,"<REDACTED>",145
ATA  <------ answer the call
OK

^DSCI: 3,1,3,0,<REDACTED>,145

+QIND: "ccinfo",3,1,0,0,0,"<REDACTED>",145  <------ call set up
AT+CREG?
+CREG: 2,1,"E183","<REDACTED>",7  <------ still on LTE

OK
ATH  <------ hangup
OK

Based on those findings, I think the radio/modem/codec part does a good job, but the UAC interface somehow limits sample rate or other PCM settings.
I’ll happily test and report if the issue is fixed in the new firmware.

Thank you!

5

Dear @omik ,

Good Day,

I understood your point, i be sending the latest firmware via mail, hope you may flash and test it!.

Thank You and Have a Great Day!

6

Please send the correct firware in this email shankfabulous@gmail.com
I am struggling to get 16 KHZ high quality sound, 8 KHZ sound seems like robot to another person, Please send.

Thank you in advance

7

Hi, Shashank Sharma. please send the firmware you are currently using.

8

Hi @yangwanxin ,

Thanks for getting back! Here are my module details:

  • Module: Quectel EC25-E
  • Firmware (AT+QGMR): EC25EUXGAR08A08M1G_A0.303

I are using this for 4G VoLTE voice calling with Asterisk.

Could you please share the latest EC25-E EUXGAR firmware update package (e.g., EUXGAR08A19M1G or latest) along with the QFlash tool? I specifically need the build with updated UAC PCM audio fixes and 16kHz support over USB.

Thanks,
Shashank Sharma

9

Hi, I have sent the latest firmware and Qflash tool to your this email, pls chk

10

Hi @Shashank_Sharma and @Grzegorz_Buczynski could you please share the 16 kHz firmware with the QFlash for the EC25-EUX Quectel?

My mail sergii.povzaniuk@gmail.com

Thank you!

11

Hi @yangwanxin and @Alvin295337,

I would like to follow up on my previous request regarding 16 kHz USB/UAC audio on the EC25-EUX.

My module details:

  • Module: Quectel EC25-EUX
  • Current firmware: EC25EUXGAR08A13M1G_20.200.20.200
  • Application: Linux-based AI voice agent using real VoLTE calls
  • Audio interface required: bidirectional USB UAC / Voice over USB
  • Required format: ideally 16-bit PCM, mono, 16 kHz

I can enable the USB audio interface and use it for voice calls, but 8 kHz audio significantly limits the quality, especially for speech recognition and AI voice processing.

I saw that the latest firmware and QFlash were previously sent to users in this thread. However, it is not clear whether the firmware actually enables 16 kHz audio through USB UAC.

Could you please clarify:

  1. Is there currently an EC25-EUX firmware that supports 16 kHz USB UAC audio during a VoLTE/AMR-WB call?
  2. If yes, could you please send me the latest compatible firmware package and QFlash/QFirehose tool?
  3. If the standard firmware still exposes UAC only at 8 kHz, is there an engineering/test firmware or patch available that enables 16 kHz?
  4. Is there any AT command, for example AT+QDAI, AT+QPCMV or another audio configuration command, that allows the USB audio interface itself to operate at 16 kHz?
  5. If 16 kHz UAC is not technically supported on EC25-EUX, could you please confirm this and recommend a Quectel LTE module that supports true 16 kHz bidirectional USB audio for VoLTE calls?

I am happy to test an engineering firmware and provide logs, ALSA device information and call test results.

Thank you very much for your help.
Best regards,
Sergii