Setting mode for fax, Refer to, System settings – Sharp MX-6070N User Manual

MX-3050N, MX-3060N, MX-3070N, MX-3550N, MX-3560N, MX-3570N, MX-4050N, MX-4060N, MX-4070N, MX-5050N, MX-5070N, MX-6050N