This card is a Straight Talk Wireless SIM card (not a T-Mobile SIM card!) You cannot use this SIM with an existing T-Mobile or for a new T-Mobile account activation. You can only use it for activating your T-Mobile or T-Mobile-compatible phone with Straight Talk Wireless (straighttalk.com) with its own plans, support and customer service.
StraightTalk Triple SIM card for your Samsung Galaxy phone (T-Mobile compatible versions only!) activation on Straight Talk.
It will work for activating your Samsung Galaxy phone with a clean ESN/IMEI on Straight Talk using their bring you own device option
For activation, you will need to go to straighttalk.com (and buy a prepaid no-contract month-to-month unlimited plan)
Triple Cut SIM - Nano, Micro, Standard (Mini) in one - just punch the one that fits your Samsung Galaxy