A First Look At Microsoft’s Istanbul

Istanbul, or Microsoft Office Communicator 2005, is slated to be the next client for Microsoft’s Live Communications Server. If you have never heard of Live Communications Server, you aren’t alone. Live Communications Server has been around for a few years, but is definitely one of the lesser known Microsoft Server products.

In case you are wondering, Live Communications Server is basically a chat / instant message server. Originally, a lot of the code that is now in Live Communications Server was included in the Chat module of Exchange 2000 Server. However, when Microsoft released Exchange Server 2003, they decided to drop the chat component and roll it into a separate product instead; Live Communications Server.

What’s New in Istanbul?

When rumors of Istanbul first began to circulate on the Internet about six months ago, it was rumored that Istanbul was actually going to be the next version of Outlook. The rumor was that Outlook’s current features would be combined with integrated instant messaging and video conferencing components. Sadly, these rumors turned out to be false. Istanbul is a self contained application that is not integrated into Outlook.

Just because Istanbul does not integrate into Outlook, doesn’t mean that it completely ignores Outlook though. Istanbul can access your Outlook address book. If you want to initiate a conversation with someone, you can simply click on the appropriate contact name.

Istanbul takes its use of the Outlook Address book further than that though. The software actually maintains presence information for everyone in your address book. This means that you can tell at a glance who is and is not online. If you need to communicate with someone who is not online, you can even configure Istanbul to notify you when that person becomes available.

In addition to instant messaging, Istanbul offers features such as application sharing, file transfers, voice over IP based phone calls, and video conferencing. Best of all, all of these various communication methods are extremely flexible. Istanbul allows you to change communications methods mid stream. For example, if you are having an instant message conversation with someone, you could easily switch to a voice or a video conversation without having to end the session.

Another way that Istanbul interfaces with Outlook is that it can access schedule information. As you probably know, Outlook allows you to create a schedule for yourself and to book meetings with others. If you want to prevent someone from scheduling a meeting with you at a particular time, you can mark the time slot as Busy. Istanbul makes use of this schedule information and allows you to schedule an online conference in a manner similar to what you would use to schedule a meeting in Outlook.

The first time that I played around with Istanbul, I thought that it was basically a kicked up version of NetMeeting. After all, features such as the white board, application sharing, and video conferencing have been around in NetMeeting for many years. However, you must keep in mind that Istanbul is a client for Live Communications Server 2005. Live Communications Server is an enterprise class product. What this means is that even though NetMeeting might allow you to communicate with someone using voice, video, and maybe a shared application, a session through Istanbul and Live Communications Server can accommodate up to 32 people (counting yourself).

When you schedule a conference through Istanbul, you can have up to 32 participants. Each participant can interact with the conference using what ever method they want (instant messaging, voice, video, etc.). Furthermore, anyone can change their communications method midstream without interrupting the conference. Everyone involved in the conference can interact with a shared application or a whiteboard. This is the real power of Istanbul and Live Communications Server 2005.


All of Istanbul’s power comes at a price though. Istanbul tends to require a lot of bandwidth, especially during video conferences. I mentioned earlier that Istanbul had a lot of similarities to NetMeeting. I’ll admit that I haven’t touched NetMeeting in a long time, but older versions used to really require a lot of bandwidth for application sharing. Due to deadline constraints and the fact that this software is so new, I haven’t had a great deal of time to experiment with Istanbul. However, the general consensus seems to bee that Istanbul doesn’t consume all that much bandwidth while sharing applications. I suspect that this is probably because of the advances that Microsoft has made in terminal service communications over the last few years.

The server also has a lot of prerequisites that you must meet. For starters, Istanbul is designed to work with Live Communications Server 2005 Service Pack 1. Service Pack 1 is still in beta, but should be available by the time that Istanbul is released.

Live Communications Server 2005 requires that SQL Server 2000 with Service Pack 3 be running on your network (SQL Server 2005 will also be supported when it is released). SQL Server doesn’t actually have to be running on the same machine as Live Communications Server, but having SQL Server running somewhere on your network is an absolute requirement. A lot of applications will allow you to use MSDE in place of SQL, but that isn’t the case with Live Communications Server.

The other prerequisite that you need to be aware of is that workstations running Istanbul will need access to a certificate authority. This is the only way that Istanbul can guarantee secure communications with the server.

The Communications Infrastructure

Although Istanbul hasn’t been released yet, I wanted to take a moment and discuss the underlying communications infrastructure. This is something that you have to pay attention to in order to have a successful deployment, and if you are serious about deploying Istanbul when it is released, then the time to start planning is now.

The main thing that you need to know about Istanbul’s underlying communications is that Istanbul communicates with Live Communications Server using a protocol known as SIP (Session Initiation Protocol). SIP communications occur over TCP port number 5061.

Unfortunately, the way that SIP works prevents you from being able to use Istanbul to connect to Live Communications Server from across a firewall or through a NAT device or a proxy device. This does not mean that you can’t communicate with Live Communications Server from beyond your network perimeter though. You just have to configure Live Communications Server in a manner that will accommodate external communications.

The technique for configuring Live Communications Server to accept external communications involves setting up Live Communications Server in a front end / back end configuration in conjunction with Microsoft’s ISA Server. I don’t want to go into too much detail since this is supposed to be a preview of a new product, but the general idea is that the external user passes through a firewall using port 5061 and accesses a front end Live Communications Server. This Live Communications Server then acts as a sort of Proxy Server and passes the communication through another firewall (typically ISA Server based) and ultimately to the company’s back end Live Communications Server. The backend Live Communications Server is the same server that users within your network perimeter access. If you want more detailed information about this configuration, you can find it at: http://www.microsoft.com/technet/prodtechnol/isa/2004/plan/tls-isa.mspx This Web page actually references an older version of Live Communications Server, but I am told that a similar technique can be used for Live Communications Server 2005.

If you do want to connect external users to your Live Communications Server, then you need to know that Live Communications Server imposes some serious restrictions on remote users. In Live Communications Server 2003, remote users were able to exchange instant messages with local users, and could also maintain presence information regarding anyone using the Live Communications Server. However, features such as application sharing were unavailable to remote users. It is rumored that Live Communications Server 2005 and Istanbul will have similar limitations, but at the present time it is impossible to say for sure.


The beta release of Istanbul looks promising. Like any beta software, it does have a few glitches, but Beta 2 shows a lot of progress over Beta 1. I think that by the time that Istanbul is eventually released, it will be an excellent complement to the existing messaging infrastructure in most larger organizations.

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