What are the features a customer can avail by using appointments organizer software ?

"A customer will receive email and sms reminders (optional) about their appointments, events and they can also receive their invoices and receipts via email."

Can a customer login in appointments organizer software ?

"If the company has given you the option to login a customer can login and view their appointment history, invoices, receipts and the customer can send a request for a new booking, request for changing an appointment."