Avaya is demonstrating the iPhone version of its one-X Mobile client at Cebit, but company officials have not yet decided whether to use the upcoming SDK from Apple to enhance the application.

The iPhone version of the mobile application is available in the U.S. and comes to Europe in the third quarter. One-X Mobile lets users manage voice mail and get access to company directories and call logs.

The goal is to make the iPhone enterprise ready. But because the iPhone is a closed platform, the one-X Mobile client runs in the Web browser, completely separate from the rest of the phone. Avaya offers more advanced clients for Nokia and BlackBerry phones.

The release of the long-awaited iPhone SDK (software developer kit) this week could change all that. So far Avaya hasn't decided whether it's going to build a more full-featured client, using the SDK. A deciding factor will be how open Apple makes the iPhone.

"We will have to wait and see what's possible. Today we don't know if we can integrate directly with Visual Mail," said Stefan Döbbe, senior solution architect at Avaya.

If Avaya can only add two features it probably won't develop a new client. It's a fine balance between what it can achieve, and how many hours it will take, according to Döbbe.

In general, developing clients for mobile phones is an uphill battle.

"We have to develop a client for every phone, because the phone vendors interpret the Java substandards differently. Even phones from the same vendor work differently," said Döbbe.

He also tells a horror story about a Nokia phone that worked in the U.S., but not in Europe, because the European carrier didn't support the same software version.

Despite the challenges, Döbbe still thinks there is hope.

"The vendors are getting closer, which will make it easier for us to develop applications for mobile phones," he said.