You will need to contact your provider again and get someone on the phone who can help you. The directory number is assigned by the ISDN provider.
"The rcapi number command allows the Cisco 800 series router to reserve directory numbers exclusively for incoming calls.
The directory-number argument is the number assigned by the ISDN provider for the PC on which RCAPI is configured. The directory number should not be set to any other interfaces such as POTS and DOV. This command works only with the Net3 switch type."
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fdial_r/drfprshe.htm#1044505