Who I have the same questioned this topic

Trying to review the text message history on our bill and it is confusing me.  Some messages show whether it was incoming or outgoing and show the phone number.  Some messages do not show a phone number.  

My husband and I are on the same account and there is no log of texts between the two of us.  Is that because we have different numbers but are on the same account?  

Next question is why are there some areas where it will show that a text for instance was "incoming" but it doesn't show the phone number.  There is a number over in one column, but it isn't long enough to be a phone number.  It will show the date and time, then there is a 5 digit number and it will say whether it was incoming/outgoing.  I have no idea what this is and why the phone number isn't revealed.  

Does every text coming in/out show up on the bill (doesn't seem to)  or do they only show up if they are messages that are NOT between iphones.  I'm obviously confused.