Phone dialer icon is missing

[black bolt]

I have a Tmobile Samsung galaxy tab S2 tablet that I recently got the code to unlock the sim so I could use a different carrier sim. The code works cause I'm able to do text messages and surf the web with the different carrier sim but the only thing it can't do is make voice calls because it's missing the phone dialer icon. This tablet has never been on a Tmobile network so I can't say it had the dialer icon before. Anyone here knows a solution?