Most of us are familiar with the concept of "presence" through instant messaging, but instant messenger presence information has its limitations: just because someone is present doesn't mean they're free - they may well be busy talking on the phone.
That's why so many replies to IMs tend to be of the curt "on the phone" variety, and why many software makers are betting that integrating IM presence with telephony status information (in fact the integration goes further, but more of that later) is going to be the Next Big Thing.
If IM-telephony integration catches on - for the solid business reason that it improves employee productivity - then it's likely that you'll have to implement it in some form or other over the coming months or years. Whether this is possible and economically feasible depends on decisions you make now, so its worth taking a look at what IM-telephony integration entails.
But firstly, what exactly does IM-telephony integration mean? At the simplest level, it involves the provision of richer presence information: instead of an IM client telling you if someone is online or away (there are other status levels like "busy" but most people who are genuinely busy don't have time to use them,) it will also tell you if they are or on the phone or not.
This is useful because other features then enable you to avoid phone tag by setting a notification feature so a popup appears in your IM client as soon as they are off the phone so you can call them before they (or you) make another call.
Depending on the level of integration, you can also escalate an IM conversation to a full phone conversation simply by clicking on the appropriate button in the IM client, and use PBX functions to control calls from the IM client (for example put calls on hold, carry out ad-hoc conference calling, or even carry out conference calls using the PBX's conference bridge.)
The whole system also works in reverse for incoming calls: when you are on the phone, your IM client can tell you when someone else is trying to call you, what their number is and even who they are if there number is recognized – you can then take the call, or set it to go to another number or to voice mail – all from your IM client. If your company has a compatible IP PBX, then users of clients such as Microsoft Communicator or IBM SameTime could even be used as internal phone extensions.
So what do you need to have in place in order to be in a position to offer IM-telephony integration?
Firstly, you need a corporate IM system that can integrate with a PBX. Fortunately the big names have this capability: Microsoft's Live Communication Server 2005 can certainly do it, as can IBM Lotus SameTime 7.5, and others such as the open source Wildfire XMPP (Jabber) server, to name but three.
On the PBX side, things get a little more complicated. LCS integration should be possible using one of Microsoft's LCS PBX partners, which include Siemens, Nortel and Mitel, and others such as Cisco and Avaya. Hybrid PBXs that support IP as well as TDM may have LCS integration built in, while traditional PBXs need to be linked via a SIP-to-CSTA (Computer Supported Telephony Application ) gateway. This allows CSTA control messages to be sent via SIP from the IM client (usually Microsoft's Communicator) to the PBX. Since different PBXs support different sets of CSTA control messages, some call functions may not be available on clients connected to some PBXs.
On the open source side, a plugin for the Wildfire IM server called Asterisk-IM allows integration from the Wildfire Spark IM client (and other clients, such as Cerulean Studios' Trillian, as well) with the Asterisk open source PBX. This is more limited than, for example, the LCS integration that is possible with some PBXs but includes phone activity information, dialing from the IM client, and incoming call notification including caller id where available.
No one is going to throw away a PBX to replace it with one that is IM compatible, but it's certainly something to factor in when you come to the start of the next PBX upgrade cycle. As VoIP becomes more widely adopted, you'll probably be looking at one with IP capabilities anyway, which will certainly make integration with an IM system easier.
If you haven't adopted a corporate IM system yet then you should factor in ease of integration with a PBX during your evaluation process. It's also worth considering how important the benefits of IM-telephony integration really are. If you were planning to go with an open source solution like Asterisk for your telephony and Wildfire for your corporate IM system, would a perceived lack of IM-telephony integration features be enough to persuade you to buy LCS and all the other infrastructure required? Probably not.
The software and hardware vendors will no doubt have you spend money on their products now, but unless there is a compelling reason to do otherwise the smart course of action is probably to adopt a wait and see approach. Bear integration in mind when considering any IM or PBX kit, but don't rush out and buy anything right away if you don't need to. With any luck IM telephony integration will become a trivial networking exercise before you need to upgrade your systems next and the features integration offers will be ones you take for granted.