[exim] bind to another port?

Hello lists,

I want to bind Exim on another ip address and port other thant the default 0.0.0.0:25,ig,I like it
run on:

127.0.0.1:1025

Can you tell me how to do it by modifying the config file?
(I looked through the offical spec.pdf but can't get it).

Thanks.

--Phoenix