Am I legally obligated to provide a phone interview to the at fault drivers insurance company or can all communication be done through email?

You have no legal obligation to cooperate with the other driver's insurance company. Typically these phone interviews are taken when the insurance company is not willing to admit liability on the part of their insured and are often used against the not-at-fault driver.  We advise our clients to not agree to an interview without a lawyer present. Good luck.