Q: with my original iPhone when i was on my macbook pro i could answer phone calls and texts with the replacement phone i can't pop up on my computer says phone is not on same iCloud acct please help thanks

whenever I'm on my macbook pro and i recieve a phone call or text i could answer or reply through my macbook pro without having to touch the phone i recieved a replacement iphone6 today everything is working fine except that i can't answer or text while I'm on my computer i keep getting a popup box that says iPhone must be on same iCloud account which i thought it was after setup was finished and old iPhone6 was deleted from the accountany help is appreciated thanks