A:AnswerCheck you WiFi settings on your phone.
Something is NOT turned on.. Start with data.
And check that data limits are not set too low.
If so... It will not allow your hot spot to work.
A:AnswerI am on T-mobile and I have a Sim card and I am assuming you mean a sim card when you say service card. When I changed my phone to the Samsung it accepted my sim card with no issue as it is an unlocked phone.