On your cordless phone problem you still have to deal with the LVC issue, but 1 could easily replace them although you might want to try a different style something like the one in this post:
http://www.rc-monster.com/forum/show...7&postcount=10
They are about 1/4" longer and about 3/16" wider than 3 AAA cells. The same length as a AA and the thickness of a AAA.
Jeff