Call control is extremely important along with tone and grammer. If you have persistant lonely people calling for phone support(every major holiday, its so sad.) You have to consider cutting these customers, although Dell might swoop in to pick them up(you never know.) Polite but firm is what I try and teach my techs.

To my knowledge bobcares does not currently provide phone support.

There are a couple of other us-based options however, I haven't dealt with any of them personally so I cannot recommed them.

Keep in mind that you've got a per-minute rate for your 800 number, plus phone service. You might want to consider a virtual pbx style service for this type of application. I am a fan of aptela.com.