Google Blocks Calls to About 100 High-Cost Telephone Numbers

Google says that although it still blocks use of Google Voice to terminate calls to fewer than 100 U.S. telephone numbers with unusually high termination cost, it still does so. Earlier, Google Voice had been blocking calls to thousands of numbers in some exchanges.

In a letter to the Federal Communications Commission, Google says a June 2009 study it conducted found that the top 10 U.S. telephone prefixes Google Voice was terminating accounted for 1.1 percent of its monthly call volume, about 161 times the expected volume for a "typical" prefix. That 1.1 percent of calls also accounted for 26.2 percent of its monthly termination costs.

Google says terminating those calls costs as much as 39 cents a minute. Google therefore blocked Google Voice calls to less than 100 U.S. telephone numbers, based on that study.

The difference is that where Google had before only been able to block calls to prefixes, it now can block specific telephone numbers with highly asymmetric traffic typical of free conference call services, for example, which never place outbound calls, but simply receive them.