Reducing mobile voice and data costs is a top concern for CIOs, judging by comments at an enterprise mobile and wireless conference this week.

Jim Swartz, the CIO at Sybase, recounted -- reluctantly -- the time when an engineer showed up with a US$7,000 monthly bill for his mobile phone service.

The fee caught the attention of upper management and led to an examination of how to keep wireless network costs under control, Swartz recalled.

"Keeping mobile rates down is a big problem for many businesses," Swartz said in an interview at Mobile & Wireless Enterprise 2008, sponsored by Frost & Sullivan. "It's so easy for all of us to spend minutes and then cause an increase in costs."

In the case of the US$7,000 bill, the Sybase worker was traveling abroad where wireless rates and plans varied as the worker crossed country borders. Some travelers at Sybase today will carry several SIM cards, which each based on a different country's rate plan, that can be swapped in and out.

But it isn't exactly physically simple to swap out cards, Swartz said, so it is not an ideal solution even for those with unlocked phones. "You can imagine how difficult it is to carry around a bag of little SIM cards and then take the time to insert them one after another in a phone," he said. In recent months, Sybase has tried to make sure loaner wireless phones are available in each country.

Even though Sybase makes mobility software, the question of reducing costs while traveling abroad shows the complexity of the cost reduction issue, Swartz said. "None of this [process of reducing costs] is easy," he said.

Sybase tries to counsel workers on ways to lower costs, he said, but changes in technology and carrier service plans add to the complexity. Sybase has to manage 27 carriers, including three in the US posing "major organizational challenges."

"International mobile phone rates somehow need to be standardized," he suggested. He said mobile costs in recent years have been "creeping up" at Sybase, and are eating into reductions realized from wired networks.

Another CIO, Tim Stanley at Harrah's Entertainment, said with 50 gaming locations internationally, the company has found that cost management for mobiles internationally is "a real bear... it's just a real mess out there and we're spending a lot of money."