IPhone problem with no service?

IIm currently on straight talk with my iPhone 4. I bought an iPhone 5s but it's has "no service ". And IIm having trouble having my number on this new iPhone, that I bought on eBay.

Chances are you need to contact your phone company to activate the new phone. If you haven't already, you need to activate the SIM card. Call customer support, they will tell you to turn off your old phone to temporarily disconnect it from any network and you have to give the phone company the information of the SIM card in your new phone, which can be found in "settings" in the subcategory "general" in the "about" settings. They will most likely ask for the IMEI, CCID, or MEID. Then they will do the rest for you and your phone should start working after a few hours.