Verizon Wireless has become the first major U.S. carrier to launch ringback tones, which are music clips that replace the standard ringing sound callers hear.

Verizon Wireless has become the first major U.S. carrier to launch ringback tones, which are music clips that replace the standard ringing sound callers hear.

The service, which is available to subscribers in Sacramento and southern California, is launching with an initial catalog of more than 2,200 songs from Warner Music Group and Sony BMG Music Entertainment.

Ringback tones are available for a monthly subscription fee of 99 cents; the tones themselves sell for $1.99 each, with unlimited use for one year. Like ringtones, the fees appear on a customer's monthly bill.

Ringback tones are expected to provide a formidable revenue jolt to the music industry. In Korea, carrier SK Telecom has achieved more than 30% penetration among subscribers since ringback tones were rolled out two years ago.

Verizon Wireless expects ringback tones to be available throughout its network by mid-2005.