SIM / IEMI Combination on MC7304


I am conducting a project for a customer and have been issued 200 SIM’s for the Telstra M2M network (Australia).
Each of these SIM’s has been inserted into an embedded PC which has an inbuilt 4G Modem (MC7304).

I have come across a situation where a particular SIM / IMEI combination does not work.
The facts are;
A. I can use that particular SIM in any other device, and I can establish a login.
B. I can use any other SIM in that particular device, and I can establish a login.

It is only the unique combination of both these items causing the issue.

My thought it that either Telstra is blocking that specific combination of SIM/IEMI or there is some corruption of the SIM/Modem profile for the APN I am trying to connect to.

Is it possible that the Telstra network can perform a specific SIM/IMEI block like this ?

Is there an AT command(s) that I can use to remove the profile information stored in the SIM / Modem so I can try re-establishing ?

I am using the native Windows networking to set up the connection profile (no connection manager)

Thanks in advance.

what is the SIM/IMEI combination which is causing the issue?