Chapin, who lives in San Diego, answered his cell phone, but when this writer identified himself, the line suddenly went dead and a follow-up call went into a voice mail.

FORBES: California Sues 'Nonprofit Entrepreneur' Roger Chapin And Charity Forbes Exposed

But if your phone is receiving bits of data every now and again, some of which could be part of a voice call and some an e-mail, there's no recognisable cut-off that can be used to calibrate your bill.

BBC: Graphic

Another unnecessary cost: employees who call a company-paid 800 number to retrieve voice mail from their desktop phone instead of using free long distance on a cell phone.

FORBES: Magazine Article

If the call is missed, it's routed into a voice mail system that users can check on the Web, or via their phone.

FORBES: Google Calling