"Land line phones get power from the line to which they are connected, so
they will also work in the event the power goes out instead of running low on
battery power."
This is not true of all landline devices, many of which provide extra
features like cordless handsets and answer machines, and require plugging
into a normal power socket to function. Also, a cell phone's need for battery
power can be mitigated somewhat by buying a small solar charger (photovoltaic
panel). A friend got one from a big box retail store for NZ$15. Some MIT
researchers have invented transparent solar cells that could be incorporated
into the screens of the next generation of portable computers (of any form
factor), allowing constant trickle charging when there is a sufficiently
strong light source:
http://energy.mit.edu/news/transparent-solar-cells/
BTW I've heard that in my country there is a plan underway to abandon the
copper phone lines that support the landline experience J.B. Nicholson-Owens
describes, and replace them with fibre-optic cables to the house and VoIP. I
think this is foolish, because of the benefits of a traditional landline that
J.B. describes. But I have to admit I don't know if it's practical to
maintain the copper line network in parallel with the fibre network long
term, or what it would cost. It may be that the costs really do outweigh the
benefits.
