Google has filed a patent application for technology that lets mobile phone users click on a Web-page ad and be connected via a voice call to the advertiser.

Such services already exist but Google's application could be specific enough to win a patent, said Aaron Chatterjee, a patent attorney at Foley and Lardner "I think they have a chance," he said.

Users at the moment can wirelessly search an online database for a nearby business and then click on a link on the results page to automatically call the business. But Google's application is specific to clicking on advertisements and by narrowing the click-to-call parameters, Google could win a patent, Chatterjee said.

However, the US Patent and Trademark Office (USPTO) is fairly strict when it comes to issuing business methods patents - the category under which this application would fall.Only about one in 10 such applications are approved.

Recently, a growing chorus of experts has called for patent reform that might eliminate the award of simple or broad patents on techniques that have already been widely used. The controversy surrounding the Amazon.com case is a well-known example of the uproar caused by some types of patents. Amazon.com was awarded a patent for the technique that allows repeat visitors to its site to single click on a link to purchase an item.

While single-clicking is commonly used across the Web, Amazon.com won the patent for just one particular application of the single click. Amazon.com then sued Barnes & Noble for using the technique. The two companies settled the case.

"From a policy perspective, whether such patents are good or not, that will have to be settled in the legislative arena," Chatterjee said. "There is certainly controversy over the business method patent arena but given the US leadership in this area, I would be surprised if at least technology business method patents are curtailed in any way."

Earlier this week, the USPTO and a group of companies led by IBM announced a new program aimed at improving the quality of patents.

The Google patent was filed in June 2004 and published by the patent office last week. The inventor of the patent is named as Shumeet Baluja, a senior research scientist at Google. Google could not be reached for comment.