left a message saying that the call is not a sales call, but a personal business matter; requests a call back at 888-660-4834.

Phone call comes from this number every day in afternoon or evening; never leaves a message, never says anything when I answer the phone - have searched my Nextel/Sprint manual for any way to block out a number, but apparently, the cell phone I use does not have that option.

My cell phone number was registered on the DO NOT CALL registry the day I activated the account; this is the only number that repeatedly calls without any message.