Mobile phone content advertising is the promotion of ring tones, games and other mobile phone services. Such services are usually subscription-based and use the short message service (SMS) system to join up to them. Another method is broadcasting messages to the mobile phone's idle-screen, enabling the mobile operators or advertisers to reach millions in real-time. The advertising and sale of ring tones in particular has seen a massive growth in recent years, with some commercial breaks, particularly on music television channels and in motor racing (especially NASCAR, with Sprint Nextel as the series sponsor), being dominated by such adverts. Advertising in newspapers and magazines has also become popular. History The first easily customisable aspect of the mobile phone were the operator logos – small, monochrome images that show the logo of the mobile network operator (such as Vodafone) by default. These were often replaced by a person's name or a small symbol. As handset manufacturers introduced better ring tones and audio capabilities. The ring tones became the most common method of customising the phone. Web sites containing ring tones of popular songs and tunes started appearing, with many of them providing the service free of charge and with little or no advertising at all – their popularity grew mainly through word of mouth. However, these sites soon started charging a small fee for the privilege. The next step was to advertise these services. However, since the introduction of interchangeable faceplates on mobile phones in 1998, the mobile market has shifted its advertising strategies. Some companies started large mass media campaigns to advertise the fact that they had the latest tunes and largest collections of ring tones. One of the biggest advertiser is the German company Jamba! (known as Jamster! in some countries), known for the Sweety the Chick and Crazy Frog ringtone characters. After months of public complaints, the British Advertising Standards Authority (ASA) ruled on 21 September 2005 that many of the advertisements must be shown only after 9 p.m. The primary intention of this was to prevent the company from targeting young people in its campaigns. Trends A new trend in mobile phone content advertising is the "ad-supported" mobile phone service model. MVNO's such as Virgin Mobile USA, Xero Mobile, and Blyk offer, or plan to offer, free or subsidized mobile phone service in exchange for subscribers viewing a number of targeted advertisements that are relevant to the