I have made attendance sheets on microsoft excel and use my IPad2 at the beginning of the lesson.
I will say the students name and expect an "I'm Here!" answer.
Intermediate students will say "I'm here" , followed by me saying "Hello ____ (student's name)" and them replying "Hello, JJ"
More advanced will do the above... plus I will follow up with "How you doing?" and they will answer "Pretty, Good"
EVEN MORE advanced students will do the above and add "Pretty good, how about you?" I will say "I'm pretty good, too" and they will reply "That's nice!"