"We don't intend to have more than one backoffice for switched digital video," Kelso says.

    AsforNorthernVirginia, Cox intends to launch SDV commercially to subscribers there in less than 30 days. Sources familiar with that market say Cox originally awarded the SDV deployment to SA but later opted for BigBand.

    Kelso and BigBand officials would not comment on vendor selection activities in Northern Virginia, but Kelso did commend BigBand for getting SDV up and going quickly in that market. He says it took BigBand only six weeks to get the system installed and turned on with "friendlies."

    "We asked for a no fuss, let's-get-this-done type of approach, and it came out just that way," Kelso says.

       SDV is considered a bandwidth saver because channels in the switched tier are streamed only when a customer in a given service group selects it for viewing. Cox has not publicly defined what channels will be placed in the switched tier in Northern Virginia, but it will use SDV to free up space for more high-definition content. In June, speaking at the Society of Cable Telecommunications Engineers Cable-Tec Expo, Cox president Pat Esser said his company expects to have enough capacity this year to offer 50 HDTV channels. (See Fretting Over HD.)

    Spare capacity could also come in handy this fall, when Cox's Orange County system begins to test a service that will offer four ABC prime-time shows -- Desperate Housewives, Lost, Ugly Betty, and Grey's Anatomy -- via VOD the day after they originally air on the network. Digital subs will be able to watch those shows on-demand for free, but won't be able to fast-forward through the ads.

    How much an operator can "oversubscribe" the system with SDV is dependent on variables such as service group sizes and the popularity of programs that are available on the switched tier. On average, MSOs are using an oversubscription model of two-to-one, according to Biren Sood, vice president and manager of BigBand's cable video business unit.