Is the general rule, if you add any additional cards to the system then you have to use the external power supply
or
Is it only if you are adding Digital station cards??

What if all your phones are IP and your only adding Loop start cards?? Still need external power?

Help
Thanks
Vinny

I found out from a Vertical guy... it looks like the external power supply is only needed when using Digital Station boards...

So if the only boards your using are loop boards then you don't need it.