The eternal challenge for IT executives is deciding whether to outsource or bring an enterprise solution in-house. That's no less true in instant messaging, a space in which corporations are striving to come to terms with the technology's spread into their businesses.

Fortunately, a number of the same features are available in enterprise instant messaging offerings in both the outsourced and in-house camps. Others are unique to one side or the other.

Understanding those features and appreciating the differences in product offered by business-grade IM vendors is critical to selecting an ideal, cost-effective solution for your enterprise -- be it a smaller firm or a large-scale deployment in a Fortune 500 company.

Criteria to Consider

Before we look at what IM offerings are available, we should discuss some of the features that IT buyers should be looking for in an enterprise instant messaging system.

A primary consideration for IM applications is, quite naturally, making sure that the user logging on to your corporate IM system is who they claim to be. Many mechanisms can be used to ensure a user's authenticity, although many Enterprise IM (EIM) systems and gateways choose to rely on an underlying authentication mechanism, such as directory services, rather than utilize their own authentication system.

If you have such a system, Microsoft's Active Directory or Novell's Directory Services, for example, make sure that the EIM system you implement can interface with them. This will negate the need for company employees using your IM system to maintain more than one username and password to access both the network and IM application.

With IM becoming such a popular communications tool, it's reasonable to assume that conversations conducted via IM will, at some point, contain information that is company confidential -- even if it's just last month's sales figures or the home telephone number of an executive. For this reason, you will need an IM system that provides security for messages as they are transmitted, even if all such transmissions will be within your network.

All of the EIM systems and gateways discussed in this article provide some level of security, though some offer more features than others. Commonly accommodated features include secure sign-on, digital signatures and encryption.

A widely used feature of IM solutions is the ability to transmit files between users. Just as with e-mail, you need to make sure that files you are receiving (or sending, for that matter) are virus-free.

Because of the overhead involved with creating anti-virus systems, many EIM providers plug into third-party anti-virus products. This means that in some cases, you might get anti-virus support without having to make an additional purchase.

One of the biggest concerns with allowing IM is that it is likely to be abused by employees, rather than used for business communications. For that reason, comprehensive logging is a key element to EIM systems and gateways. In some settings, the logging may even be necessary as part of regulatory requirements -- this is true in industries like financial services.

If you have specific logging requirements, make sure that the EIM system you implement accommodates them. Be aware that not all logging systems are equal, and some offer much more detail than others -- such as instantaneous keyword flagging of suspect phrases. Also consider what formats the logging information is available in. Most EIM systems support logging to a SQL database as well as a variety of other formats.

Also worth considering is whether your enterprise IM system's logs can be integrated with your e-mail logs -- making auditing simpler by combining the systems' archives.

While all of the IM systems discussed here provide the basic IM functionality, some products are more feature-rich than others. Things to look for that you may not have considered are centralized administration of user lists, the ability to send broadcast messages to entire groups of users at a time -- useful for communications from IT administrators, for instance -- and advanced notification capabilities, including integration with wireless Short Messaging Service.

If you already use Web conferencing, look into whether your EIM offering provides similar capabilities. Other, more subtle features, may not be mission-critical, but they can add considerably to users' IM experience. For instance, customizable presence states -- which enable a user to indicate not only that they're unavailable to receive messages, but to specify that they're actually in a third-floor meeting -- can make employees' use of IM far easier and more effective.

It's easy to think of IM as a lightweight network application, and generally, it is. But like with other enterprise applications, as the number of simultaneous users increases, demands on the servers and underlying infrastructure can balloon as well.