the problem with the 600 Ohm resistor is that it is not needed if you have a proper paging amp with a T/R input.
@NortelAvayaBlue
Also using 330 Ohms instead means that whatever is internal in the IPO will take more of the energy and might kill your board over time faster as you have higher amps but less energy on the resistor meaning higher amps on the internal circuit so more energy there.
I have never had the need for a resistor except in the old IP400 days when I plugged one in to reboot to activate the paging port but that one I took out when installing the IPO permanently.
I really don't get these workarounds, why do that rather than using proper parts designed to do the job. The part is called WMT1A and you get it for $30-45 depending where you shop.
People treat paging like rocket science but it is not, it is simple and straight forward and requires sometimes the reading of the manual delivered with the parts like zone controllers, pre-amps etc but it is still as basic as it gets. Basic electronic knowledge doesn't hurt but even that is not all that important because there are only 2 different interfaces for the input and a few (usually well labelled with 25V, 70V and some with 100V) output interfaces.
There are probably 100 threads here over the last years all with the same issue, weird but true.
The time it takes to post here and wait for answers compared with having a WMT1A in the truck and test it with that is huge so my advice to all techs get a WMT1A from your boss or if you are the boss buy one. It will save you a lot of time one day in the near future and it is not a patch job like a resistor punched down with the wires of the IPO output.
I have done so many service calls that should have been a 10 minute job but took me 2 or more hours because I had to fix wiring that was falling apart as soon as I started troubleshooting due to these shortcuts that I am really absolutely against stuff like that.
Rant end sorry if that sounds like a personal attack, it is not.
It is a general statement expressing my aversion against any kind of shortcuts in live. But let's not get into that one as the number of my pet peeves are too many to write in a thread. That would require a book.

A really thick book
Joe W.
FHandw, ACSS (SME), ACIS (SME)
“Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skillful execution; it represents the wise choice of many alternatives.”