I have a need for an ISDN BRI line for dial-backup purposes on a hosted/managed router at my site and I am having problems finding a provider to supply use one BRI line. They seem to not want to deliver anything smaller than a PRI line. We already have PRIs into the building and one of them is terminated in a Cisco IOS router acting as a voice gateway. Is it possible to split a BRI line off of that PRI line in the IOS voice gateway and use a DID number for inbound calls to route to it? If so, what is necessary from a parts and configuration stand-point? It seems logical but I don't know for sure and voice is relatively new to me.