Encouraging staff to use Skype or Wi-Fi when outside Canada, will help as well.

However, Tauschek admits senior executives often see themselves as above these kinds of restrictions.

There's always showing the executive his most recent wireless bill, Tauschek added. That worked for a Toronto company whose senior salesman hadn't realized he'd chalked up a $1,500 roaming bill the last time he was in South America. "Part of it is user education," Tauschek said.

But Tauschek said real-time services such as offered by Anomalous Networks warn managers fast before they get hit by bill shock.

Anomalous Networks' CEO Daniel Rudich said he and co-founder Jaan Leenet created the service because other expense management solutions rely on data coming from wireless carriers, which can delayed by up to several weeks.