Verizon Is Mapping a New Road to Riches

"The dedicated GPS device will have a harder time," says Entner. "People are drowning in different gadgets. And charging them all becomes the difficult part to manage. There's more utility having it all in one device."

Among the telcos, Sprint (S Quote) and Verizon Wireless -- co-owned by Verizon (VZ Quote) and Vodafone (VOD Quote) -- have taken the lead on GPS. Both offer navigation service on certain phones for $10 a month, an additional charge not covered in the subscribers' monthly data fee. Verizon also has a $3-a-day option for those who use it infrequently.

AT&T (T Quote) and T-Mobile, a unit of Deutsche Telekom (DT Quote), have only recently introduced GPS devices for a couple of phones.

A Verizon representative declined to say how much its VZ Navigator service brings in for the company, but he said it was catching on.

The test for the telcos will be finding services such as email and GPS that help boost the all-important average revenue per user, or ARPU, figures.

Though no one can specifically point to the GPS contribution, it's notable that Verizon Wireless has seen its data ARPU grow 158% in 2006 to $7.91, from $3.06 in 2005. Meanwhile, AT&T, formerly Cingular, saw data ARPU grow a more-modest 53% over the same period.

Unlike MP3s and grainy cell phone pictures, the phone companies may have pinpointed a billable service that users can't easily detour past.