No messages in iMessage on MacBook air

I currently have an I phone 8+ and a MacBook Air. I do not get any messages on iMessage on the MacBook but all messages come through fine on the iPhone. I have tried signing out of iMessage on the MacBook and tried signing back in and I get a message that states “could not sign into iMessage in error occurred during activation try again“ this problem actually started occurring when I switched iPhone 6 Plus is with my mom. We had identical models of iPhone and mine had a bad battery. Both of us backed up our phones to iCloud and switched The Sim cards. After the switch my moms phone, which was mine, was restored perfectly. But After the switch I was unable to get any messages on my MacBook Air, even though they were coming through correctly on the iPhone. This problem has continued even after the purchase of a new iPhone 8+. When I sign out of iMessage on the MacBook Air and sign back in under someone else’s Apple ID, my dad for instance, his messages to come through I message on the MacBook Air just as they do on his iPhone, so I know it is not a software issue. But I am unable to sign into iMessage on the MacBook Air with my Apple ID as I get The message stated above.