My HTC Thunderbolt one day decided to not send or receive phone calls but i am able to use the internet. Also, i am not able to send out SMS with a error message stating, "Would you like to send when digital service is available?" but i am able to receive SMS txt messages. When i do call my phone, it either go straight to voice mail or it rings to voice mail depending on the day i try. I took it to verizon and they changed out my SIM card and my phone still did not work. I dont know whats causing my phone issues. Is it possible to fix it internally?