Using Diald in a server?

Is there a way to setup my ppp server to use diald to call any of the
computers on its subnet whenever there is traffic for that PC? I am
trying to use a ppp server to provide remote access to web-enabled
sensor computers using a PPP connection. I have the sensors setup to
call the server when they have traffic, but we would also like to be
able to visit the sensor anytime we feel like it and this required my
ppp server to be able to call a specific sensor. Each sensor as a
static IP on the network and the traffic is all generated in my
network. Is it possible to use NAT and still get access to these
sensors from outside my LAN?

Thanks for your help and ideas