EC25-EUG: IMS PDN up but no SIP REGISTER on a private LTE network – request for latest firmware and a VoLTE MBN

IoT Modules LTE Standard Module
1

Hello,

We are testing VoLTE with an EC25-EUG mini-PCIe module on a private LTE network (band 3, private test PLMN, EPC + IMS core).

Module

  • Firmware: EC25EUGAR06A07M4G_01.001.01.001
  • MBN: Commercial-DT-VOLTE (selected manually, AutoSel = 0)
  • AT+QCFG="ims",1
  • PDP contexts: CID1 internet, CID2 ims (IPV4V6)

What works

  • The module attaches; the Attach Accept advertises “IMS voice over PS session in S1 mode: Supported”.
  • After AT+CFUN=0/1, the module opens the IMS PDN by itself (CID2, QCI 5). AT+CGCONTRDP=2 returns the IP and the P-CSCF address from the PCO.
  • AT+QPING to the P-CSCF over the IMS PDN succeeds (3/3, ~57 ms).

The problem

  • The module never sends a SIP REGISTER. A capture on the S1-U side shows no SIP traffic at all over 8 minutes; only our ICMP pings.
  • AT+QCFG="ims" stays at 1,0 (not registered).
  • With ROW_Generic_3GPP, the IMS PDN is not even opened.

We suspect the DT MBN only enables the IMS client on Deutsche Telekom PLMNs.

Questions

  1. Could you share the latest firmware for this module (EC25EUGAR06A11M4G or newer)?
  2. Is there a generic or open-market VoLTE MBN, or an MBN template, that does not restrict IMS to a given operator’s PLMN, for a private network like ours?
  3. Otherwise, which settings (NV items or AT commands) need to change so that the IMS client registers on a PLMN that is not in the MBN?

Thank you in advance.

2

I have sent the latest firmware to your email, pls check and try again