I know few business people who make intensive use of their mobile that does not work with two lines, which usually implies in case of having an iPhone the fact of carrying two mobile phones, which is a bit boring at times.
Line2 is the VoIP alternative to carrying two telephones. They offer us a fairly good service of calls and voice messages through the use of the 3G or WiFi network, thus having a second line on the iPhone.
The negative or not so beautiful part is the price, which goes to 15 dollars a month for the fact of having the line enabled, and they are paid through an in-app purchase, which in turn is worth 0,79 euros.
Source | YouM
It does not appear in the app Store, it will be in the US. Has anyone tried it anyway?