What I have seen here in L.A. is that the BB position, whether there or not is in the hand and has to post, there is no 'sitting out', unless it was stated before the hand was dealt, and a Sit-Out placard (like the All-In placard) is placed on the table at that position. If not, that player has to post. If he sat out, he would have to buy-in to the next hand with a bb and possibly the sb if it was a short call. Or he could wait till the next bb.
But because he was dealt cards, and looked at them, I would rule him out of the hand even if he wanted to be in the hand and he owed the BB. He took the phone call. That put him out of the hand and owing the bb.
I haven't looked lately, but I sort of doubt whether Roberts Rules covers cell phones.......