got new sim in mail

Joel CaLdWeLl wrote:

I bought a SIM card and it says that's connected and in service yet when I go to SIM card it says phone number unknown and won't let me make calls or connect to data can anyone help figure out why

The SIM needs to be activated for your service.  Give Customer Care a call at 611, which will work even if the SIM isn't active, and make sure you have the rest of the SIM card holder because you will need the number off of that.  You can also reach out to T-Mobile via DM on Facebook or Twitter but calling should be a lot faster to get your SIM activated.