phone calls and texts

I had a old iPhone 8plus that i decided to set up as my new phone because its better then my current iPhone 6splus. I fully reset the iPhone 8 and set it up with my apple id from the 6. I noticed after the 8 was set up it didn't have service so i thought if i took out the sim card from the 6 i will have service. For some reason it didn't work so i took it out and put it back in my iPhone 6. And now I cant make or receive phone calls and texts on either phones.