Can't send group text with MacBook Pro error message: Phone number "not registered with iMessage"
I am on a group text with four friends. I don't have a problem texting on my iPhone, but when I try to text them on my MacBook Pro two of four recipients names are in pink rather than blue and I get an error message that the text cannot be sent because one number "is not registered with iMessage."
I would appreciate suggestions as to why this is occurring and how to fix it.
iMac, OS X 10.11