[Q] XPS 10 WAN -- just AT&T or T-Mobile too?

I had to send my WiFi only XPS 10 in for repair. It was replaced with an XPS 10 with cellular WAN capability. It came with a complimentary AT&T micro SIM card.

I am a T-Mobile customer. Does anyone know if can I use the device with T-Mobile, or is the device “locked” to use only AT&T? Can the device be unlocked to use T-Mobile?

Thanks in advance,