Independent wireless retailers are facing their own set of challenges in an era when carrier-owned and big-box stores have moved to the fore. In this interview, Mike Mohr, the head of wireless retailer Celluphone, talks about his 30-year history in selling phones and how independent dealers are coping. The biggest challenge? "We're past 100% penetration. That is the tipping point that triggers a lot of other things, particularly volume and margin pressures," Mohr said.