Rebtel announces findings from its mobile device survey conducted online on its behalf by Harris Interactive, which measured American adult mobile phone and tablet users’ sentiments and observed trends concerning mobile devices, as well as spending on International calling.

According to the study, 88% of American adults own a smartphone, standard mobile phone and/or a tablet device, with 18% claiming they own a tablet, and 41% claiming they own a smartphone.

In the U.S., over 1 in 5 (21%) U.S. adult smartphone owners make international calls and are responsible for paying the bill. They spend an average of $156 every month doing so. Surprisingly, amongst the men and women polled, there are vast differences in what they spend on international calls, with women averaging $267.10 a month, and men averaging $85.50 (or 320% less).

According to the 2010 U.S. Census[1], there are 234.6M adults age 18+ in the U.S. With 41% of the population claiming to own a smartphone, and 21% of these making international calls on their smartphones, this works out to roughly 20 million Americans shelling out nearly $38 billion a year[2] on international calls on their smartphones annually.

Here are some other key highlights of the study:

• 35% of adult Americans who own a tablet and a smartphone claim to have a VoIP app for calling; One quarter (25%) of Hispanic Americans surveyed who own one of these devices say they do, as do 17% of the African Americans surveyed.
• 8% of male respondents who had a smartphone and were responsible for paying the bill last year indicate that they plan to spend more on their cell phone bills this year compared to last year; while 29% of female respondents who had a smartphone and were responsible for paying their bill last year indicated the same.
• Hispanic Americans surveyed who are responsible for paying their smartphone bills and ever make international calls indicate that they pay substantially less than Black/African Americans respondents in this survey ($144 vs. $206 a month, respectively).
• Age plays an important role in tablet ownership, but varies widely between genders. Men ages 18-34 were the least likely among all age groups to claim tablet ownership with only 11% claiming to have one, whereas females 18-34 were twice as likely as men (22%) to indicate this.

Based on all respondents surveyed, men and women are nearly identical when it comes to smartphone ownership, with 41% of women and 40% of men claiming to have one. Women respondents were slightly more likely than men to indicate owning a tablet device, 19% vs. 16% respectively.

Breaking down the mobile gender divide

In terms of VoIP apps for calling, 35% of U.S. adults who have a tablet and smartphone say they have one installed for calling on either a tablet or smartphone device, with 41% of men indicating they have one and 30% of women saying the same. This seems to follow along spending expectations, where 40% of men surveyed who own smartphones and were responsible for paying their bills last year say they plan to spend less than they did last year, while only 20% of these women surveyed expressed their plans to do so. Juxtaposed to this, only 8% of these men surveyed said they plan to spend more this year than last year, where nearly three out of ten of these women surveyed (29%) indicated they expect to spend more than last year.

Ethnic breakdown: Hispanic and Black/African American respondents

The study also took a look at two of the most heavily represented ethnic groups and found that 29% of Hispanic smartphone owners surveyed make international calls and are responsible for paying the bill, whereas 36% of Black/African American respondents surveyed say they do so.

Of the two groups, Hispanic Americans who are responsible for paying their smartphone bills and ever make international calls indicate that they pay substantially less than Black/African Americans respondents in this survey ($144 vs. $206, respectively). Furthermore, only 30% of Hispanics respondents who own a tablet or smartphone claim that they have a VoIP app for calling and only 21% of Black/African Americans polled claim to have one.