The fifth caller from Washington wasnt identified by either company, presumably because he is living in a furnished apartment where phone service is supplied by the landlord.

A small Boston Globe test of caller ID accuracy found several instances in which Verizon Communications and Comcast Corp.

The price is minimal on a per-call basis - often a penny or less a call - but spread across a telecommunications giants many customers, it can quickly run into the tens of millions of dollars.

Santoro. Were giving customers as much as anyone could give them without making it cost prohibitive for us.

Comcast spokeswoman Shawn Feddeman said the cable giant contracts with a national database company for its caller ID services.

She said it was her understanding that the company buys name data from most telecommunications companies.

Caller ID is a hugely popular service, allowing consumers to see the name and number of who is calling so they can decide whether to take the call or return it later.

For a company such as Verizon, caller ID information is easy and inexpensive to retrieve in its own service area because the caller is probably one of the firms own customers.

On its Web site, Verizon explains that the caller ID service will not always generate the name and number of the caller.

When that happens, the Web site says, a message will be displayed explaining why.

The messages vary depending on the customers display unit, but Verizon identified out of area or unavailable as messages that would pop up for calls made from outside specially equipped areas and calls made through an operator.

The messages private or anonymous would appear for calls made by people who have blocked the display of their telephone information.

Industry officials says its also difficult to identify the names of people making calls using operators, toll-free numbers, or from businesses with their own phone systems.

Names are also not available for consumers with dial-around long-distance service or customers of telecommunications companies that dont store name data, including many wireless carriers.

We dont think this guys data is worth the money, Santoro said.

He said Verizon charges 1.6 cents for each calling name Accudata purchases.

But, he said, Accudata would be willing to charge Verizon half that.

Smith said Accudata spends more than 1 million a year purchasing data from Verizon.

To test whether caller ID customers are getting their moneys worth, the Globe arranged for five people to call numbers in Massachusetts belonging to a Verizon and a Comcast customer with caller ID.

The Verizon customers caller ID was able to identify only the caller from New York, who presumably was in Verizons database.

For the other four calls, only the state the call was coming from was identified.

The Comcast caller ID correctly identified the callers from New York and Missouri and listed the other three as unknown name.

Verizon and Comcast said they couldnt provide names for the two Texas numbers because they were in Accudatas database, and neither company purchases data from Accudata.

Verizon didnt come up with the Missouri name because it doesnt purchase name data from Southwestern Bell Co., which is now part of ATT.; Comcasts caller ID provider did purchase the Southwestern Bell name and the Verizon name.

Caller Id Per State Vicidial