To offset this cost, it hosts small ads that appear in the messaging windows. The way AOL sees it, no one else should have access to that advertising space and revenue. Some providers, such as EarthLink Sprint, have worked out deals with AOL whereby they offer AIM's network to their own users. Yet it's not fair to say that this is akin to Microsoft tying a browser to an operating system. In that case, a consumer needs both in order to run a PC and surf the Internet.
Instant messaging is an auxiliary service.
It's possible to be on the Internet and use instant messaging without being a paying AOL subscriber. And AOL argues it has good reasons for keeping its network closed. The company says it would run a huge security risk if its service were to become compatible with some other programs. Opening its network to any company that wants compatibility would mean lowering its security wall and perhaps allowing spam to take hold, the company says. If spam became a problem in instant messaging, it would ruin the experience, says AOL's McKiernan.