I only have a mobile phone from T-Mobile, no land line. $29.99/mo for 300 anytime and unlimited weekends. For as much as I care to use the phone, this is basically unlimited.
While in college, I worked in a T-Mobile call center for almost 2 years (yeah, that sucked), and the "I COULDN'T HAVE USED THAT MANY MINUTES!!!" was always my favorite type of call.
The one call in particular that stands out is when a mother called about text message charges on her bill that she didn't expect. They were sent/received on her daughter's phone, and she had me list the times that the messages happened. I listed off several date/time ranges, most of which were during the week when her daughter would be in school, to which she replied that this was impossible because it was against school rules for her daughter to be using her mobile phone in class. It took a lot of self control to not let a laugh slip out after hearing that one. After explaining that the phone's serial # was recorded with each text message sent, and the few that I checked did match her daughter's phone, she decided she'd talk with her daughter and call back later.