EC25-J (EC25JFAR06A04M4G_DCM): QPCMV uplink audio works only on the first VoLTE call after reboot - request latest standard firmware

IoT Modules LTE Standard Module
1

Hello,

Module: EC25-J Mini PCIe (EC25JFA)
Firmware: EC25JFAR06A04M4G_DCM
Network: NTT docomo, VoLTE (MBN: Commercial-DCM_VoLTE, AT+QCFG=“ims” returns 0,1)
Host: Ubuntu Linux, USB (option driver, ttyUSB0-3)

What works:

  • VoLTE outgoing call (ATD:wink:
  • Remote DTMF detection with AT+QTONEDET=1 (all keys 0-9, *, # are reported)
  • Downlink voice over USB with AT+QPCMV=1,0 (we receive 8 kHz 16-bit PCM on ttyUSB1)

Problem:

  • Uplink voice (host → ttyUSB1 → remote party) works ONLY on the first call after the module reboots (AT+CFUN=1,1).
  • From the second call on, the remote party hears silence, although all PCM frames are written to ttyUSB1 without errors and downlink still works.
  • Things we tried that did NOT fix it: keeping QPCMV=1 between calls (never sending QPCMV=0), keeping ttyUSB1 open across calls, AT+CFUN=0/1, re-setting AT+QAUDMOD, AT+QDAI and AT+QMIC.
  • AT+QPCMV=1,0 returns ERROR if sent after the call is connected, so we send it before ATD.

Requests:

  1. The latest EC25-J standard firmware (non-DCM) that supports VoLTE on NTT docomo, together with QFirehose (Linux) or QFlash, and the flashing instructions.
  2. Does the newer firmware support USB Audio Class (UAC) on EC25-J? AT+QCFG=“usbcfg” does not show the UAC parameter on our firmware.
  3. Is there a known fix or workaround for the uplink issue above?

Thank you.

2

The firmware for _DCM was not found. I have sent you the latest standard firmware version. You can try to refresh it and then give it another try.

3

Hello,

Thank you very much for sharing EC25JFAR06A06M4G_01.012.01.012 via SharePoint. I have downloaded it and the MD5 check passed.

Before flashing, I have two questions:

  1. My module currently runs EC25JFAR06A04M4G_DCM. Is it OK to flash EC25JFAR06A06M4G_01.012.01.012 onto this module directly?
  2. Could you please share the latest QFirehose tool for Linux (Ubuntu 24.04, x86_64)? It was not included in the package.

Thank you for your support.

4

I have sent the qfirehose to your email, pls check and try