One of our classmate could not edit their name with out adding address and phone number. Is the address and phone number required?

The system was changed to require either a complete mailing address, or no mailing address. So Classmates can't select a state without a city, or a city without an address. They don't have to provide an address at all though, they can get past that by removing the incomplete parts of the address that are in there. It's interesting that they asked you about this though, as when they tried to save an incomplete mailing address the system would have popped up a message informing them that their mailing address was incomplete, and to either remove it entirely or complete it.

The reason we don't want incomplete addresses in the system is things like the "show classmates on a map" feature and the upcoming labels feature requires a complete address. Plus there's other reasons admins might need a complete address. Mailing addresses are never shared anywhere in the system by default, nor are they shown on the classmate map.