Unified Messaging – Exchange 2007-Part1

In this blog you all have seen lots of content talking about exchange 2007 like what is Exchange 2007? Which are the different roles? What are their functions? And even Exchange High Availability.

In this article we will purely focus on Exchange 2007 – Unified Messaging. Well, before we could get into this stuff. I would like to share my scope for this Unified Messaging. From this article you will understand some basic concept and definition about the unified messaging (theoretically) and some illustration which will show you how to configured unified messaging – demo and configuring your unified messaging server
Note: This is purely a lab setup to make you understand about the concept, in real time there might be some other changes you might require to do.

Well, Unified messaging is a new feature in Exchange 2007 which has been developed by Microsoft by taking consideration about today’s technology and high demand for the mails. In simple term what I could understand about unified messaging is, it is system which stores voice message, email messages and fax receiving.

What is Unified Messaging?
Unified Messaging service helps the client to read their messages, contact, calendar & fax receiving from a mobile device or any telephone system. This unified message use text-to-speech to convert the mailbox content into speech.

By using this unified messaging you can perform the following functions:
 You can check your e-mail message, calendar and contacts over the phone
 Can search user’s information in the gal by accessing the unified messaging.
 Can check the calendar, respond to the calendar events and even we can re-schedule it.
 Can make the availability of meeting room & location from the telephone.
 Can check the voice message over the phone.

Features of Unified Messaging:
Just remember these four words SCAF
S – Subscriber Access
C – Call Answering
A – Auto Attendant
F – Fax Receiving

Subscriber Access:

 Subscriber Access is nothing but a way to communicate with your unified server who will guide to either access your mailbox or to guide how to contact someone. Subscriber Access is almost like a receptionist who is sitting in the office to assist some one to get in touch with right person. As I told you it has two major functions either it will open your mailbox for you or help you to get connected with your respective contact person.
When it is connecting to your mailbox, it will ask for your telephone extension and then it will ask a pin number for your mailbox access. Once it do a validity check it will give you the following information like new email message, voice mail, email, calendar, personal contact or directory & personal option. From the telephone keypad or voice itself you can customize your personal options like – Changing the Pin, time zone, time format, turning on telephone out-of-office & voice user interface. Even users can reply, forward or delete their e-mail messages. He can accept, review or decline his meeting

If you want to connect to some other users, you have to just dial the extension number, it will direct you to that specific number and if that person is not at his desk it will ask you to drop the voice message.

Call Answering:

 Let say UserA calls User B but UserB is not at his desk, in this scenario Unified Messaging Server will answer a call on behalf of a mailbox owner and it will record the message and finally it will deliver to the mailbox owner or it will redirect to other user who has write access for that user. The way it works.. External users call one internal user, this call will be routed via IP/pbx or VoIP gateway  to the destination users, if the destination user is not available, this call is then routed to Unified messaging server. Unified Messaging server will take a message from the external users, if he place the voice message and then it will deliver it to the mailbox server. If user is unable to place the message it will notify the mailbox owner with missed call notification.

Auto Attendant:

 Auto Attendant is nothing but exactly like a receptionist who is sitting in an office. It will help us to do certain automate actions like call forwarding & call answering. These services allow the user to access the user account which is located in the gal. When a person call it is re-direct your call to unified messaging server if the destination user is not available. It will ask you to use the keypad for user name, or alias name or extension to redirect the call and even you can leave a voice message for the destination users.

Fax Receiving:

 You have the ability of voice fax or receive fax message in a .tiff format as an attachment. For delivering the Fax it uses the T.38 Protocol. The way it works is external user will send a fax which will delivered to Unified messaging server by mode of IP/PBX or VoIP gateway. UM server will query the active directory for the destination user information and then it will forward it to Hub server as an attachment and finally it will get reside into Mailbox server of that mailbox account.

Telephony Solutions:
There are 3 main types of telephony solutions

1) Centrex – In this module each user will have a standard analog phone line that is directly connected to the Central Office aka CO and the call will be routed directly to their extension number. This kind of solution is feasible for small organization

2) Key Telephone System -
  In this module, organization will lease several lines from the telephone service provider and all of them will be routed to each of the phone in the organization. When an incoming call comes, all the phones will ring at the same time, there will be one receptionist who will accept the call and forward to respective extension number.

3) PBX –
A PBX (Private Branch Exchange) is nothing but leasing multiple phone line from a telephony provider rather then having phone line for each and every users. By having this PBX we can call our users internally without involving the telephony provider. Whenever we make a call for external user, it will automatically choose the available line for us rather we select it.  This PBX is being used in many organizations as it is helping the organization in terms of reducing the cost. When any users call up via pbx it will establish the connection and it will drop the packets when the transmission gets completed i.e maintaining the connections as long as the users require them. In addition with this we can set auto attendant, auto dialing, dial plan, hunt group, call forwarding, call waiting, conference call etc.

     There are 4 types of PBX:
             Analog : By this mode we can send voice and signaling information.
             Digital : It will use the industry  standard audio code G.711.
             IP/PBX :  IP/PBX support voice over data networks. This is used where we have nic card, ip will convert the voice mail into digitalized packets and place the packets on the data network it is sent by packet switching.
             Hybrid PBX: It is nothing but the combination of digital and ip/pbx.

Switched Network:
 Exchange 2007 unified messaging can be used by Circuit switched network and Packet-Switched Network, it depends.

Circuit Switched Network:
 This will set up a fixed bandwidth connection until the call gets disconnected. Once the call gets disconnected it will make available for other users conversation. It uses T1 or E1 lines

Packet-Switched :
In this mode the packets are routed independtly from the source to the destination. It is nothing but a dynamic bandwidth.

Protocols used for unified messaging:
There are 3 main protocols

SIP: Session Initiation Protocol, this is used for establishing connection on an ip based network. It major function is to use to create, manage and end communication.

RTP (Realtime Transport Protocol): it is an Internet Engineering Task Force (IETF) standard protocol that is used for unified messaging to route the realtime streaming data such as voice or video.

T.38: T.38 is an International Telecommunication Union (ITU) standard protocol that is used to send fax messages over IP-based networks.

Call Process:
 External User place a call for an internal users
 It will use PBX route to route the call to the internal user by using circuit-based network.
 It route it to the internal user, if internal user is not available then it will return back to PBX.
 Based on the coverage plan, it will take an action what next to do with that call. If my planning rules specify that it should forward the call to unified messaging then it will forward the call to Unified Messaging through IP\PBX or VoIP gateway by using SIP for session and then it will use RTP to send the information
 Then my call will get converted into packets to the unified messaging.

If a user is not available on his desk:
 UM Server will given an option to leave a message for the destination users
 Hub Server will accept the message from unified messaging server by mode of smtp.
 Then it will forward it to the mailbox users by resolving the user information from CAS server.

To understand the unified messaging features and definition click here

I hope this article has given you the basic overview of Unified Messaging Server. In my next article I will show you how to configure the Unified Messaging Server for receiving a call, configuring auto attendant, subscriber access and sending a voice message to user mailbox and even a demo video.

Related Article:

Configuring Unified Messaging Server – Exchange 2007 – Part2

Reference Link:

Private branch exchange 

Getting Started with Outlook Voice Access 

Getting Started with Exchange Server 2007: Server Roles

Plan your Exchange 2007 Backups based on Server Roles