• by Mark Walsh  @markfwal, June 30, 2011

Is midday the best time to run advertising on mobile phones? According to the latest monthly data from Jumptap, that's when ad interaction rates peak on the mobile ad network. Conversely, click-through rates are at their lowest during the morning commute and early hours of the workday.

Separate research has shown that mobile data use -- especially mobile video viewing -- takes place throughout the day as people "snack" on handheld media when they get a chance. Around lunchtime is one of those times, helping to boost ad engagement.

The Jumptap data for May also showed that mobile ads increasingly feature calls to action other than clicking through to a branded Web site. More than a third (34%) of performance-based campaigns included a click-to-call option or download offering rather than directing the user to a Web property.

Separate monthly research released Thursday by rival mobile network Millennial Media provided further detail on the types of calls-to-action employed in mobile campaigns. Overall, more than half (54%) drove traffic to a company Web site, 28% to an application download, and 18% to a custom landing page.

When it comes to post-click options in ads, the most popular were click-to-call (used in 42% of campaigns), an invitation to sign up for an offer or service (34%), retail promotion (25%) and some type of social media feature. Use of social media in ads to acquire followers or gather feedback on movie releases or new product launches was up 36% in May over April.

Marketers were more frequently adding a store locator to post-click options. This feature was included in 22% of campaigns in May, representing a 48% monthly increase.

Among targeted campaigns on the Millennial network, nearly half (48%) were locally tailored, while 38% were aimed demographically and 12% behaviorally. The company said education-related advertisers, for instance, used demographic targeting to reach so-called Millennials about degree and certificate programs, while financial services companies ran ads for student loans and credit products geared to college students.

On the Jumptap network, Android continues to gain share. The Google smartphone platform generated 42.4% of ad requests -- up 3% from the prior month -- while Apple iOS was roughly flat with a 30.3% share. Rounding out the top three was Research in Motion's BlackBerry OS, at nearly 21%. But that proportion was down 4 percentage points from April.

Information released Wednesday by InMobi showed a similar pattern, with BlackBerry's share of impressions dropping to 13.8% in May from 18% in February. Android's share, by contrast, grew from about 30% to 30.5%, while iOS jumped from 15.5% to 25.4%.

According to Nielsen's May survey of smartphone users in the U.S., 38% own Android devices, 27% have an iPhone, and 21% have a BlackBerry phone. While Android has overtaken iOS in the last year, the Apple platform enjoys the highest average click-through rates of all mobile operating systems, according to Jumptap.

Its findings were based on some 11 billion ad requests made across its network reaching more than 83 million unique users. Millennial says it reaches 92 million U.S. mobile users and 142 million worldwide.