GSM and LTE-M connection with SIM7070G for MQTT data transmission

Question

I am working on a tracker project using the SIM7070G modem from SIMCOM. The objective is to maximize the connection by working with both LTE-M and GSM, aiming to send location data via MQTT.

I have successfully configured the modem to establish a connection and send data using LTE-M. However, I am encountering difficulties when trying to achieve the same with GSM. To simplify, I've provided the sequence of AT commands for both scenarios. Note that I've omitted MQTT configuration AT commands (AT+SMCONFG) for brevity.

For LTE-M:

---> AT+CFUN=1
<--- OK
---> AT+CNMP=38
<--- OK
---> AT+CNMP=38
<--- OK
---> AT+CMNB=1
<--- OK
---> AT+CPIN?
<--- +CPIN: READY
---> AT+COPS?
<--- +COPS: 0,0,"Movistar",7
---> AT+CEREG?
<--- +CEREG: 0,1
---> AT+CGATT?
<--- +CGATT: 1
---> AT+CNCFG=0,1,"gm2m.movistar","gm2m","gm2m",0
<--- OK
---> AT+CPSI?
<--- +CPSI: LTE CAT-M1,Online,722-07,0x0A65,134173954,17,EUTRAN-BAND4,2000,3,3,-7,-73,-53,24
---> AT+CNACT?
<--- +CNACT: 0,0,"0.0.0.0"
---> AT+CNACT=0,1
<--- OK

+APP PDP: 0,ACTIVE
---> AT+SMSTATE?
<--- +SMSTATE: 0
---> AT+SMCONN
<--- OK

For GSM:

---> AT+CFUN=1
<--- OK
---> AT+CPIN?
<--- +CPIN: READY
---> AT+COPS?
<--- +COPS: 0,0,"Movistar",0
---> AT+CGREG?
<--- +CGREG: 0,1
---> AT+CGATT?
<--- +CGATT: 1
---> AT+CGDCONT=1,"IP","gm2m.movistar"
<--- OK
---> AT+CGAUTH=1,1,"gm2m","gm2m"
<--- OK
---> AT+CPSI?
<--- +CPSI: GSM,Online,722-07,0x0a29,4313,798 PCS 1900,-87,0,16-22
---> AT+CGACT?
<--- +CGACT: 1,0
---> AT+CGACT=1,1
<--- OK
---> AT+CGPADDR=1
<--- +CGPADDR: 1,10.36.89.229
---> AT+CGDCONT?
<--- +CGDCONT: 1,"IP","gm2m.movistar","0.0.0.0",0,0,0
---> AT+CGACT?
<--- +CGACT: 1,1
---> AT+SMSTATE?
<--- +SMSTATE: 0
---> AT+SMCONN
<--- ERROR

I attempted the same, replacing:

---> AT+CGAUTH=1,1,"gm2m","gm2m"

with:

---> AT+CGAUTH=1,0

However, the result remained unchanged.

The issue arises when using GSM. While AT+CGPADDR returns a valid IP, the AT+CGDCONT? response shows an empty IP. Do you notice any errors or issues in the AT command sequence that could help me establish a GSM connection and successfully send data via MQTT?