I have a CenturyLink LD PRI circuit that has trouble with channels locking up. The process is very slow because it takes months between episodes where all the channels are locked. Somehow the channels show idle to the provider however the Axxess considers them busy. If I unplug the span from the card and plug back in everything resets and we are good for another few months. The ISDN switch type is set to DMS 100 but the provider is telling me that the switch is a DMS 250. They suggested I check to make sure the "service messaging" is turned on. Of course there is no flag or anything called service messaging. Any thoughts on this?