By Mark Ward
BBC News website technology correspondent
Search giant Google has sent an instant message to its rivals with the launch of its Talk service.
Google is arriving late into the net talk business
Unveiled on 24 August, the Google Talk system unites net telephony with an instant messaging network and builds on the Gmail e-mail service that was released in March 2004.
According to figures gathered by ComScore Media Metrix, America Online has more than 40 million users on its AIM and ICQ instant messaging networks. Yahoo has 20 million users and MSN Messenger has 14 million. Some of these services have been operating for more than a decade.
On net telephony, too, Google has a mountain to climb. The biggest net telephone (or voice over IP) service is run by Skype which currently claims to have 51 million users.
One of the ways that Yahoo Broadband in Japan won customers was by bundling net telephony with the net access service.
Google may have a leading share of the search market but it is a minnow when it comes to these two technologies.
What it hopes will help attract users to its instant messaging system is its offer of compatibility with the relatively closed networks of its rivals.
AOL, MSN and Yahoo try to ensure that their users talk to no others simply because they fear that opening up their networks will dilute their hold and reduce the amount of cash they can generate from all these people.
Although users can connect to other networks via more open clients, they typically lose some of the features, such as webcams and audio, that work on pure IM networks.
By contrast, Google Talk is based on an open technology called Jabber which was created to help different networks talk to each other.
Georges Harik, director of new products at Google, hinted that this was its aim when the Talk service was unveiled.
"We are going to try to be the first in the world to connect everyone to everyone," he said.
However, Google Talk does not yet use these features of Jabber and, for the moment, is as closed as any other network. Similarly, its net telephone service currently works only for GMail account holders.
On net telephony services, it also has a long way to go to catch up with rivals not least because managing a system that can provide good quality phone calls is very different to letting people scour a database with search queries.
But there is method to Google's seeming madness. It is clear that Google is trying to build a cluster of programs that effectively turns the net into an operating system - just like Windows does for personal computers.
Google wants to turn its collection of services and add-on programs such as the Desktop Search sidebar into a helper that users can turn to no matter what they want to do.
Google's Desktop Search has mutated from simple search software into a holder for lots of small applications that users can access as long as they have access to a web browser.
Both the instant messaging and net telephony services work via the floating Sidebar of Google Desktop Search.
These developments also make sense of all the rumours floating around about the creation of a Google browser.
As web watcher Jason Kottke points out, it is clear that this ability to get at your stuff and use it where ever you are is becoming increasingly important to more people. It is portability rather than being tied to a particular computer that is important.
As he also points out, it is clear that Google rivals such as Microsoft, Yahoo and Apple are pushing toward the same goal.
The reason they want to get people using their system rather than a rival's is simply because that control means they can get more advertising cash from them.
Yahoo recently bought Konfabulator which specialises in making software that can be used in lots of different web browsers.
Also, both Google and Yahoo are keen to open up the coding interfaces to their core systems and services so that the others can create useful ways to use them.
Net telephony service Skype has announced its intention to open up its network in a similar way, too.
The time for talk is over, now we have to watch the action.