Mobile advertising is exploding, and Boston is at the forefront with companies like JumpTap and Where boasting big time mobile ad numbers and expanding into markets across the globe.

Today another Boston area mobile company, Livewire Mobile, announced expansion of its mobile ad services. The company is now enabling carriers — their current customers like Sprint, Vodaphone and Virgin Mobile — to play targeted marketing messages while callers like you and I are waiting to connect with someone else or on hold.

Subscribers must opt-in to the service, and will be rewarded by carriers for doing so (although the announcement doesn’t dive into specifics around how). Those who do subscribe will hear and engage with targeted audio commercials instead of ringing or music when waiting for a call to connect.

Today’s announcement expands Livewire’s suite of mobile marketing services, allowing carriers to monetize what is known as “ringbacks.” According to Juniper Research, this ringback space is expected to be a $780 million market by 2015. Dubbed Ringspot, this Livewire mobile ad solution is powered by Adfortel’s (a company in the Netherlands) VoiceAds Engine technology. The service will hit in the second quarter of this year.

Livewire, founded in 1983 and formerly known as NMS Communications, provides services to mobile operators, equipping phones with a suite of services like ringtones, full track music downloads, video downloads, and other content. The company provides this content alongside an integrated storefront and also offers these carriers service and content marketing.

“Our Ringspot service is designed to allow carriers to take part in mobile marketing, one of the market segments with significant upside growth potential,” said president and CEO Matthew Stecker. “Livewire Mobile continues to develop innovative platform and service offerings providing the broadest range of value-added services.”