Apple's iPhone has attracted half of the world's smartphone traffic share and 55 percent in the US after it hit the market 28 months ago, mobile advertising network AdMob said on Monday in its October report.

The San Mateo, Calif.-based firm wrote in its report that half of smartphone advertisement requests worldwide were served by Apple  in October, while 24 percent by Nokia devices and 12 percent by devices from HTC.

The iPhone served about 55 percent of smartphone ad requests in the US, followed by 20 percent choosing HTC devices and 12 percent using RIM's handsets.

The AdMob statistics is calculated by measuring traffic on more than 15,000 web sites and applications.