Telephone line cords are reversed (generally) and data patch cables are straight through. If you have been using straight through cords on digitial extensions, you may not have a problem if the system is not polarity sensitive. Also using straight through cords on POTS analog lines is not a problem, it just reverses tip and ring but works fine. However, if you use straight cords on properly wired jacks with a digital system that IS polarity sensitive, it won't work. Also most two pair systems where you have data on the second pair and voice on the first pair won't work with a straight line cord. Basically if it is flat satin cable, the modular plugs should be reversed. This also lessens the chance of someone using this flat satin stuff for data connectivity.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com