Our landline has become our business phone, the number we give to people we do business with. Cell phones are for calling each other, especially when one of us is away from home. The landline is also for the kind of conversation that requires high-quality sound - with a person who is hard of hearing, for example, or infrmation security; I don't talk to the bank, the doctor or the finance guy on the cell phone unless it's to say I'm late for an appointment.