Interoperability in the Real World, Part 2

By Oren Libis

Last time, I tried to explain my view on the GCF test cases. As these are test cases that you need to pass before deploying your product (by going to GCF test labs), no matter how farfetched they are, you need to handle them. But there are another important interoperability issues that the GCF doesn’t handle. These are the real deployments out there today.

There are a large and growing number of 3G handsets out there and they are coming from several handset vendors. Each one has its own behavior and quirks. You’d be amazed how much effort it takes when you develop a 3G-324M stack to handle all of these quirks and how much you need to invest on the codec level and application level to get things done right.

Difference in behavior

This difference in behavior happens due to the complexity and richness of 3G-324M. Granted – it does only a video call, in a straightforward enough scenario, but the amount of options that this single scenario has is almost unlimited:

• It supports multiple types of codecs each with its own set of configurable parameters
• There are H.245 messages flowing
• Media quality needs to be handled differently by the various media systems out there
• Different developers have implemented 3G-324M, each one understanding the standard in his own way

Server side equipment

There are also servers on the network. These most of the time are using circuit switched networks in front of the handsets, where they are running 3G-324M, but they are also using IP based standards such as H.323 and SIP on the network side, when interacting with media servers for example. They have a different kind of behavior than handsets and they have a different decision making processes designed into them, bringing in more interoperability issues to bear.

What do you do?

The most important suggestion I can give developers of 3G-324M products is to do the GCF test cases that they must in order to get validated, but to focus and invest a lot on the handsets and servers interoperability. Try to get your hands on as much information as possible during your development regarding the differences in behavior of the handsets and servers and make sure you test against as many handsets as possible before you try to deploy your product through an operator.

Technorati Tags: 3G-324M, WCDMA, Interoperability, GCF, Oren Libis

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