Registering GPRS device with carrier

Question

I am trying to get a IOT device to communicate using GSM GPRS. Forgive me if I doing something that is blinding obviously not going to work here.

The device is a weather station https://www.makerfabs.com/open-wind-statation-gprs-mqtt.html It is a Cortex M0+ based board with some sensors and an A9G GPS/GSM module. http://www.ai-thinker.com/pro_view-28.html

The device and GPS/GSM works in that I can program it (it is the same as an Auruino Zero), read sensors, update the display, talk with the A9G and receive GPS messages.

The problem is getting the device to use GPRS. I have a sim from redpocket, using their 'GSMA' which is the AT&T 3G GSM network (as far as I can tell). The sim has a data only plan, so no voice or SMS is possible. The redpocket account shows the SIM number and an assigned phone number. If I query the A9G it shows the same SIM number.

The odd thing is that the redpocket shows 'Device ID' and a 15 digit number along with a description 'Apple Watch Series 6 A2294 big'. The 'Device ID' number does not match either the IMSI or IMEI I gets from the A9G. So I think either the redpocket 'Device ID' and description was left over from a previous subscriber (don't know how) or the A9G is defaulting to identifying as the Apple Watch. This is the area where I am a little fuzzy - the exact method the device on a data only plan uses to sent it's details to the network.

The important commands and output I get from the A9G is as follows:

>ATE0
OK
>AT
OK
>AT+CCID
+CCID: xxxxxxxxxxxxxxx
>AT+CIMI
xxxxxxxxxxxxxxx
>AT+CGSN
xxxxxxxxxxxxxxx
>AT+CREG=2
OK
>AT+CGATT?
+CGATT:0
>AT+COPS?
+COPS: 2
>AT+CSQ
+CSQ: 14,99
Signal strength -85 dBa
>AT+CMEE=1
OK
>AT+COPS?
+COPS: 2
>AT+CGATT=1
+CME ERROR: 50
>AT+CGDCONT=1,"IP","CMNET"
OK
>AT+CGACT=1,1
+CME ERROR: 148
>AT+MQTTCONN="xxx",8883,"xxx",120,0,xxx,xxx
+CME ERROR: 53

The error really is at >AT+CGATT=1, which returns CME ERROR: 50 'Requested facility not subscribed'. So I wondering if there is a magic step where I send the device ID to the network, or set the APN. My next step is to look at CGDCONT and see if any of those commands help.

Here's the A9G feature datasheet http://www.ai-thinker.com/Uploads/file/20190711/20190711185227_10118.pdf and info page https://ai-thinker-open.github.io/GPRS_C_SDK_DOC/en/hardware/a9g.html There is a manual, in Chinese, as the ai-thinker link is broken.