Those metrics really are hard to come by. When I first started covering mobile four or five years ago, many marketers suffered metrics shock when their first SMS efforts came back with responses numbering in the hundreds or low thousands. I recall a book publisher's first mobile campaign tied to the major release by an A-list author. The program had a dedicated Web site, a novel voice callback execution, and was not lacking in press coverage. But when I followed up with the mobile marketing company behind the campaign weeks later, they blanched a bit when I asked about the raw numbers of mobile responses. Off the record, the marketer admitted the publisher had to be talked down a bit after seeing the initial number of opt-ins (low thousands) with all the usual explanation.

I have learned to recognize the cover fire some marketers lay down when I ask about specific numbers related to their campaign: "It is early days." "The learnings will be invaluable moving forward." "But these folks who did opt-in are our core customers with a great multiplier effect." "The user feedback loop alone was worth the effort."

All of these explanations are true in some measure, of course, but they are no substitute for a raw head count. Misguided as it may seem, once you get beyond the bubble of mobile marketing in which we live, most of the agency planners I ask continue to say the same thing about our beloved platform: it isn't happening at a scale that matters to them yet.

Arguably, the scale actually is here already. The problem is that not enough successful marketers are giving us the kind of raw, crude, eyeball-counting benchmarks that help move budgets. Last week Nielsen issued a new white paper (which they blog and link to here) that gives us some valuable performance benchmarks.

Much of the press reported the top-line metrics, that we now send more text messages than we do make calls on our phone. But deeper into the study we find some Nielsen estimates on the actual reach of some brand SMS campaigns. For instance, The My Coke Rewards loyalty program lets user accumulate points for the Coke products they buy, and the mobile component has them add to their account by texting in product codes. In Q3, Nielsen says that AT&T and Verizon networks alone saw 1.1 million unique users sending and receiving messages at a rate of 32 per month. Think of the CRM opportunity just within that kind of volume -- reminders, merchandising, tune-ins for special events. When a user's regular input of codes starts to flag, isn't that the time to send a mobile coupon?

In sheer volume, Coke is exceptional, but other major brands are seeing real scale even in the early days of their SMS projects. Domino's Pizza had about 552,000 users on the AT&T and Verizon networks texting them in Q3, according to Nielsen estimates. Pizza Hut has 279,000 and Papa John's 182,000. Foot Locker's VIP Program goes to 306,000, while Subway's FreshBuzz news and promo service embraces 212,000. Keep in mind these are Nielsen's estimates only across the two top carriers.

In addition to sheer volume, the interesting thing about these campaigns is the age spread. Nielsen found that across free text texting exchanges with brands, 53% of customers were over 35. In fact, if you look at the age breakdown of the call vs. texting numbers, it is only in the 45- to 54-year-old demos and older that the rate of calls outnumbers texting. That is right. Even 35- to 44-year-olds are sending and receiving more SMS messages than they are making and receiving calls.

The next time a senior agency executive tells you mobile doesn't scale, ask him if having a quarter million of your best customers interact with you (not just listen to you) each quarter is scale enough. All of the Nielsen examples involve highly integrated programs that offered users the mobile option at many touchpoints.

The fundamental approach is so different from "buy this." It is closer to telling consumers, we have something of value to you (convenience, discounts, etc.), so "let's talk."  At some point, the question among marketers should stop being, how well does mobile perform and start being, how well is a creative team working to activate the ongoing conversation with customers that mobile best activates?