I think phones have a major benefit in the classroom for students who use translation features and text to speech for writing. Students can also use the phone to access language and vocabulary building apps like Duolingo in order to learn English as a second language. When students take a picture of a text and can translate that picture in real time, They do not have any delays to their learning in their native language nor in their English language acquisition.
It should be allowed but some kids might be smart enough and use there smartphones for stuff like fake fire alarms. But its okay to use your smartphone. You can get the answers from google, Or if you don't want to be rude to the teachers job (of teachings kids and not obeying it) then google has videos on how you do the math and not just the answer, So yes.
In this era of technology, There are many resourses in the classroom that assist in the learning process. Phones are not needed period. They offer opportunity to cheat, Distract, And cause other problems in the classroom. Teachers have enough difficulty keeping students focused on learning the material that he or she is trying to give to the students. The teacher doesn't have the time to monitor everyone's phone to make sure they are not texting friends, Cheating, Watching tv and other distractions. Most if not all classrooms have computers for that can get all the information that the students need to be successful in the class. If not, There is the good old textbooks and dictionary that always have the information that you need.