Visual and voice advertising startup Apptera on Wednesday announced it raised $10.5 million in a fifth round of funding led by returning investor Lightspeed Venture Partners, Alloy Ventures, and Walden International.

The San Bruno, California, company said it will use the money to further develop its mobile-advertising network, which helps marketers reach targeted demographics directly on their cell phones and hit them with “relevant” advertising.

The seven-year-old startup, which also announced that former Yahoo sales executive David Kamstedt will join its board of directors, claims to send millions of advertisements each month.

Mobile ad startups got much attention recently with companies such as Transpera and Amobee Media Systems, and Blyk also raised funds.

The emerging mobile ad market is a lucrative arena already eyed by major players Google and Microsoft, and competing against the two giants might prove to be a difficult task.