how can i get older version of skype onto iphone 3g?

[MacDoxy]

hi
i want to use skype as a landline alternative.
i got an old 3g iphone and i read the new skype has problems with the older ios. (4.3.5)

i found oldapps.com but idk how to get that d/l working on the phone??
(i can d/l it onto mbp- but then what? thx)

any help would be great

ultimately i just want something i could use on the iphone3 to call (and receive calls from) landlines

any ideas?