The call is not prohibited in the US. Many mosques are just scared to do it. We do it in my neighborhood Mosque. The neighbors wuld actually get mad if we didn't as it has become the Alarm clock for the neighborhood.

It also gives the former shower singers an opportunity to spread their wings and go in front of a live audience. :-)

In some places they add As salaatu khayru mina naum at the end of the Fajr. Is it considered a bid'a- innovation here in the Gulf?

Act your age not your shoe size