Answer:
Okay here it is..
We can use cellphone to call the police, ambulance, fire brigades etc. If you ban the cellphone no help will arrive. If we have any homework, we can write it down on the cellphone or any notes. You can entertain kids if they are bored and play some songs so you can sing along with them. If there is any show you can give the cellphone so that they can look trough the camera as a mirror. You can take photos and keep as memories. There is lots of helpful stuff. So let's not ban cellphone and I am sure they will come in good handy.