Regarding call bills and billing scenarios, which of the following statements is correct () (multiple choice)
A . The CDR data will eventually need to be imported into the CDR database
B . Users can query the bill data through the web page of the U1900 unified gateway
C . In the CDR integrated network, the third-party billing system is used as FTP Client
D . A single bill server can store and process bill data from multiple IP PBX hosts at the same time
Answer: C,D