iMessage on Mac but not iPhone

I recently swapped my iphone for a samsung galaxy but still have imessages on my macbook. I was hoping to still be able to use imessages on my macbook, however, I am unable to sign into imessages with my apple account, i get the following error:

Could not sign into iMessage. An error occred during activation. Try again.

This has been happening for a week. Can I use imessages on my mac, or must I also have an iPhone?