I'm hoping someone can help me out. I'm very confused as to when Pri-group vs. ds0-group should be used. My understanding is that pri-group should be use when the telco is delivering a PRI with SS7 equipment to your location, and that ds0-group should be used when a CAS line or channelized T1 has been delivered. Recently I've run into situations during testing where a given router would tell me that I did not have enough resources to create a pri-group, but would let me create a ds0-group without incident. Hopefully someone can provide a better explanation than what I have received previously as I am very interested in understaing this concept better.