This is posted by Surojit Chatterjee, Senior Product Manager, Google Mobile Ads team(link).Here is the excerpt-
I’ll always remember my first cell phone—a big, black brick that was really only good for making calls. While technology certainly has advanced since then, I still appreciate the speed of connecting to people and businesses instantly over the phone, something that I found harder and harder to do when I searched, for example, for the number of a restaurant to make a reservation.
So in June of 2009, a few engineers and I pooled our 20% time and worked to develop a prototype of what would eventually become Click-to-Call for smartphones, an ad unit that makes it easier for people to connect to a business by phone, rather than through a website.
Building the feature was the easy part; essentially, we developed an ad extension that allows advertisers to include a phone or location in their campaigns. However, it was launching it to advertisers that posed the biggest challenge.
With new products like Click-to-Call, we often choose to launch in beta, and incrementally roll out the features to a small subset of users, usually beginning at a 1% test and increasing from there. With Click-to-Call, we’d developed a mobile feature that we wanted to launch as soon as possible, but since mobile advertising was much smaller at that point—then with only about one-sixth as many search queries we get today—we calculated that it would take nearly three years to roll out to 10% and around 10 years to actually launch it. At that rate, the feature would likely become antiquated long before it ever officially launched.
So I decided not to follow the usual process and took a risk, choosing to launch to 50% of Google’s mobile advertisers within the first week. In my view, there was simply no other way to collect enough feedback in a short period of time so that we could quickly iterate based on feedback. Thousands of advertisers—an unprecedented amount for a brand-new feature—were on board to try it out, and with a few engineers and some pretty massive spreadsheets, we started to see real results. Within a month, we had the magical ingredient—momentum—and from there we were collecting enough feedback to be on track to bring the feature to all advertisers in a matter of months.
This is one of the reasons I work at Google. Google gives me freedom to experiment, ownership of my ideas, and amazing resources and support. We built Click-to-Call in June 2009, began testing it in July, and had it up and running for all advertisers in January 2010. One year later, Click-to-Call ads on both search and the Google Display Network are generating millions of calls every month on mobile phones and driving strong performance for advertisers.