EG91 concurrent MQTT & voice call

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.

What is the specific model of your module? Do you support 2G+4G signals? Your sim card also needs to support 2+4G signals.
Best wishes

thanks Felix

we’re using the EG91-EXGA-128-SGNS

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)