Amp'd Mobile Inc. said on Monday that consumer electronics retailer Circuit City Stores Inc. would sell its mobile phones, as start-up wireless service Amp'd expands its distribution.

Privately held Amp'd rents network space from Verizon Wireless to offer mobile phone services to young customers who pay in advance for phone calls and music and video downloads. It said Circuit City would sell Amp'd phones and airtime in more than 600 of its stores beginning October 1.

Amp'd, which kicked off its service late last year, said this month it had nearly 50,000 customers and was on track to have a customer base of 100,000 to 150,000 by Christmas.

Other companies using a similar business model include Virgin Mobile USA, a venture of Virgin and Sprint Nextel Corp., and Helio, owned by SK Telecom and EarthLink Inc.

Verizon Wireless is a venture of Verizon Communications Inc. and Vodafone Group Plc.