Can someone tell me if "is to ... " means "is going to ..." ? For example, "please enter a

number where the system is to call you to notify of incomming calls" equals "please enter a

number where the system is going to call you to notify of incomming calls" (???)
Also, does "enter a

number where the system is to call you to notify ..." mean that the system will use the

number (you entered) to call you to notify of incomming calls ?
Is the “where the system is to call you to notify of incomming calls ” called a (dependent) adverb clause of type “place” that answers question “where” ?
Thank you.