I have ordered 3 pri's from my telco and they are asking me this question but I am not sure what this means. I know for sure we don't want to do NFAS signaling.... Unless i am not understanding what NFAS really does...
"Exception Please confirm configuration,Order is requesting 3 spans as NFAS no backup D, Cisco builds are usually configured as FAS. Thanks"
You probably don't want to run NFAS. FAS is the opposite of NFAS, so you would want that.
NFAS increases complexity and you are also forced to use H323/SIP. You save a couple of B channels at the expense of it being a true pain for implementation.
Your experience may vary.