I am using an EG91 to connect to two MQTT brokers which send & receive around 1 message a second and am also attempting to make a voice call using the ATD+....; command.
The device is nominally “idle” and when the voice call is triggered both the incoming and outgoing MQTT connections pause for various amounts of seconds (between 5 and 30 at least). this then causes my code to detect as a connection drop and begins to reboot the modem. this causes the call to drop.
The “pause” sometimes happens during the ringing (both incoming & outgoing), sometimes happens during the call itself, and sometimes happens due to the AT+CHUP command.
Both my quectel technical reps have gone silent over the last two weeks.
I can’t tell how to work out if the sim is a specific generation but I don’t think it is (it’s a general consumer multi-network voice & data SIM, that can successfully make calls and use data)
I know this was a while ago but the problem is your network is using 2G or 3G for voice calls. You can send:
AT+CREG=2
…to give you network change notifications. You will see it go from +COPS: ???,7 to +COPS: ???,2 or +COPS: ???,1
You need a network with working VoLTE to make a call and keep the data connection alive. You can query the VoLTE with the following:
AT+QCFG=“ims”
…it should return +QCFG,“ims”,1,1 or something like that. The 1,1 is the important bit. Find another network or try to get VoLTE running. The easiest way would be to send these two command but it might stop any calls or SMS working (especially if you’re on Vodafone)