Default i747m Hangs Up Call Right Away

When I call someone using my phone (Telus i747m), sometimes when I press call the phone changes to the "calling" screen and then hangs up immediately with a beep sound. I've never had this problem until I lost my IMEI because I flashed a wrong network. I manually injected the IMEI back. Ever since then, once in a while it does this. I have to restart my phone and then it's fine. Also, LTE does not work anymore on my phone. It shows LTE and it is on but the reception is 1 bar no matter where I am. Any input would be helpful.