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!