Mine

I want to encrypt the incoming digits in "BOX A"
and send them to "BOX B" and then in "BOX B" I want to decrypt them and dial...
For Example:

1- BOX A : receives digits 666777888@IP_Address
2- BOX A : encrypt 666777888 to 111222333 and send them to "BOX B" 111222333@BOXB


1- BOX B: Receives 111222333 and decrypt them back to 666777888 and Dial......


any help wud be highly appreciated...