Hello Quectel Support,
I am investigating an LTE SMS-over-IMS issue using a Quectel RM520N-GL module.
Requirement
We must send MO-SMS over LTE using IMS / SMSoIP. We cannot use 3G fallback, SGs/NAS workaround, or disable IMS.
Current behavior
SMS works correctly on 3G/WCDMA.
The SMSC is correctly configured.
The destination number and AT command flow are valid.
LTE registration is successful.
IMS registration is successful on LTE.
VoLTE / IMS service is working.
On LTE, the modem attempts to send the SMS as a SIP MESSAGE over IMS/SMSoIP, but the IMS network rejects it.
PCAP evidence
In the PCAP trace, the modem sends the LTE SMS as a SIP MESSAGE over IMS/SMSoIP:
MESSAGE sip:<SMSC_NUMBER>@ims.<operator_domain>;user=phone SIP/2.0
with:
Content-Type: application/vnd.3gpp.sms
In the same PCAP trace, the IMS network rejects the request with:
SIP/2.0 482 Loop Detected - S - 16026 Dubious destination
The modem also reports the failure cause as:
Requested service option not subscribed
Based on this, the issue does not appear to be related to the SMSC, destination number, or AT command syntax. It appears to be related to the IMS SMS-over-IP profile, MBN configuration, IP-SM-GW routing, or MO-SMS-over-IMS provisioning.
Current MBN situation
The current MBN list does not include a dedicated Orange Spain profile. The currently active profile is:
France-Commercial-Orange
The available relevant profiles include:
France-Commercial-Orange
ROW_Commercial
TEF_Spain_Commercial
ROW_Generic_3GPP_PTCRB_GCF
other generic/operator profiles
I tested the available relevant profiles, including:
France-Commercial-Orange
ROW_Commercial
ROW_Generic_3GPP_PTCRB_GCF
TEF_Spain_Commercial
The issue remains the same.
I found that newer Quectel firmware / MBN lists may include:
Spain-Commercial-Orange
Could you please advise how to obtain and install the correct Orange Spain MBN / IMS profile for this module, or confirm the correct IMS SMS-over-IP NV/MBN configuration required for MO-SMS over IMS?
Please note that IMS must remain enabled, and the required solution is SMS over IMS / SMSoIP on LTE.
Module information
Module model: Quectel RM520N-GL
Firmware revision: RM520NGLAAR01A08M4G
Hardware revision: 20000
Current active MBN: France-Commercial-Orange
IMS status: registered, AT+QCFG=“ims” returns 1,1
RAT: LTE
LTE SMS format: AT+QCFG=“ltesms/format” returns 1
SMS over 3G/WCDMA: working
SMS over LTE/IMS: rejected by IMS network
Thank you.