"Je vous mets sur haut-parleur."
Translation:I am putting you on speaker.
For me, "loud speaker" implies a PA system. "I'm putting you on speaker" is a very common, if somewhat idiomatic expression in Australia.
There is an option to report a problem with the sentence. Click the flag icon and there will be one or two options. One is "My sentence is right", the other is "There's something wrong with this sentence", where you have to explain yourself.