IoT personal project modem – AT commands

Hello, I am trying to use a raspian pi 4 along with a usb lte/3g modem along with USMobile. Ssh to control pi along with nano/screen.

I was trying to mimic a service like twilio but on my own. An sms pipe of sorts since I will be sending closer to a 1:1 ratio of messages.

I want to be able to receive/send sms and extract the info such as sender or smsc center to block or activate a device or auto delete a message.

I was able to send an sms in both Text and PDU mode. I am not able to read messages except that I did it once. It returned 2 messages but I have never been able to replicate the steps cause at the time I didn’t understand how to scroll back on screen and I closed the window. I was trying to learn AT commands at the time as well so a lot of mistakes.

PDU mode: AT+MSGR causes an ip to return. AT+MSGR=0 returns error AT+MSGR=? Returns OK

Text mode: Retrieving either says OK or causes signal to display and it loads indefinitely.

I have made sure I am reading/writing to the sim and when I send a message to my device I can see that 1 out 30 slots are in use when it was 0 before.

I just can’t seem to access that memory space or if I am then it is not showing me the result of it since it just returns “OK”