Use Cell Phone To Set Up Ebay Sellers Account How Do I Set Up A New Sim Card In A Used Cell Phone?

How do I set up a new sim card in a used cell phone? - use cell phone to set up ebay sellers account

I have my phone with the SIM card, so I need both. I have an active plan with T-Mobile, despite the temporary suspension, because I have no telephone. Replacement with T-Mobile is too expensive and I know that I get a new T-Mobile SIM card from T-Mobile on eBay. I wonder how I can configure the new SIM card with a new cell phone or hand on mine?