Feasability of Serial functions and constantly running progrms

After upgrading to RedHat 8.0 and effectively breaking some python caller-id script that I have no clue how to fix.. I'm curious of whether or not PHP would be able to get caller-id data from a modem.. I imagine it could, and probably won't be too difficult to overcome... but I am posing that question just to get any feedback of any problems.. What the real question is about... is there any solid way of keeping a PHP script running (to latch onto the modem and constantly monitor it, of course...) and have it run without it crying about too much memory being used or being run too long. Any ideas, insight, etc? --Jason