Pretty sure my current pharmacy has a no-phones policy, but I don't generally use my phone in public so I haven't really noticed.
At my previous retail job I had to wait on them no matter what, but I would stand there quietly for 20 minutes holding up the line until they looked up and then say "and you're paying... how?"
My mother, who works at a different establishment, will also stare blankly ahead until either phone-person stops their conversation or the person behind them in line yells at them. Mom's co-worker responds to them as if the conversation is with her. Mixed results on that one.