I have a Nortel BCM 50 with PRI ringing in on all phones, whats happen 2 to 3 times a day a incoming line only rings in on the Prime Station and no where else. Customer says it the 800 #, but the 800 # should be pigback off incoming #s, what I'm I missing ?

Too many variables without knowing the setup/programming on site.

How do they know its only the 800 service line?
Does the 800 line point to a separate target line (DID)?

Make the Prime Set = None
Make sure there is enough appearances on the sets to answer the calls in case more than one 800 call comes in at the same time.

If they're sure it's the 800 line, then it sounds like the 800 number is not forwarded to the main line but is sending it's own digits - try building a target line for the 800 number's received digits & assign all the extensions that should be ringing.