Problem Description:The system that you have to analysis and design, using an object oriented approach, is a basic voicemail system. The voicemail system is an independent system that interfaces with an already implemented telephone system (i.e., assume that the telephone related hardware, software, and API are available ready to use). The main goal of the system is toact as a messaging service for an organization-wide telephone system. The organization may have several telephone numbers and multiple calls active at a given time.The voicemail system gets activated after a callers dialed number to the telephone systemgoes unanswered for a given number of rings (e.g., five rings). The telephone numbers are uniquely mapped to mailbox numbers. Note that some numbers may not be assigned valid or active mailboxes (or none at all). Assume that the telephone system is responsible for functionalities such as establishing and managing the connection, managing the call (e.g., pickup, hang up), and providing information from and to the caller (e.g., the pressed phone keys, and obtain and play the actual voice message). An exampleof the interface to the phone system is given bellow (you may assume that all interface calls are blocking and as such the message system will wait until the interface call has completed execution and a value returned):

PhoneSystem

pickup() //Initiates one end of a connection

hangup() //Ends a connection

dial(char)//Allows dialing of 0..9,#, *

play(message)// Paly

messageconnection(): Boolean // True if a connection

existsrecord(int): message //Record a message until

hangup() or time limit is reached

getRingCount(): int //Returns the number of rings

getDial(): char//Returns the character dialed (0 if buffer is empty else 1)

getExtension(): string //Returns the current extensionT

he voicemail system must support the callers to leave voicemails, and the mailbox owners to access and retrieve their voicemails. The owners can access and administer their mailbox with the followingoptions:Local access: from their own (local) phone devices via a hotkey on the phone device Remote access: from other (remote) phones via dialing phone and/or extension number Web or email access: via subscriptionThe caller can record a message verbally. The message is ended with a call hangup or a timeout in number of seconds. There is also an administration mailbox with extended functionality to manage the email system. This mailbox can access and manage other mailboxes (e.g., add or remove a mailbox and set a users password).

Tasks to do:1.Identify the main use cases including actors. Then, please provide the use cases diagram(s).

2.Identify the main classes and the relationships between them. Then, please provide the classdiagram.

3.Describe a scenario (per functionality) that can occur in at least three functionalities. Thus, please provide three sequencediagrams.You can use any UML design tool (to draw the diagrams) such as ArgoUML,UMLet...