Almost every advertising company makes more of banner ads. SellAring is one of company that makes sound ads and claims it gives good CTR and ROI.
SellAring is based in Israel and works with huge brand advertisers, like FOX, Vodafone and NBC. Their process is easy, they transmit the ad between the time gap when a person calls, and until their call is picked up. Later, they see a screen with call to action screen, which gives them a way to go to advertiser’s website by just one click. They provide you the chance to gain eCPMs up to 5X higher than industry standards