“doesn’t it”/“don’t they” with “every” as a determiner
Which of the two is correct: “Every cell phone does that, doesn’t it?” or “Every cell phone does that, don’t they?”
Solution 1:
Every cell phone does that, doesn’t it? or Every cell phone does that, don’t they?
"Every" is a distributive determiner as reflected in the fact that it selects a singular 'head', hence "Every student is here", not *"Every students are here".
"Cell phone" has singular "phone" as head, so singular tag "doesn't it?" is the one you want. Note that you can use a plural tag with "all": All the cell phones do that, don't they?.