I have not had any dealings with T-Mobile, but for other US carriers, I have told them I want to activate a hotspot device and here is the IMEI number for it. Sometimes they want to see the device and other times they have not. You also need to tell them it is for business and not personal use and that should get you a better level of service from the carrier, but not always. The nice thing about the new MG52 is that you can now provision the ESIM on it with AT&T directly from the Meraki dashboard and never have to speak with anyone at AT&T. Right now it's $65/month for 100 megabits of bandwidth on AT&T and it says that coming soon that will increase to unlimited bandwidth for $65/month.