4 KudoZ points awarded for this answer. Comment: "Montefiore, thanks for supporting my version, but for some reason I'm paranoid that it's not quite right (probably because I don't understand much about telecommunications in either languague :)))) -- so I think I'll use Michael's version, since he knows the subject well. :) Thank you very much, guys! I have no idea how on earth I'd cope with these texts in the middle of the night without your help."