Regarding call bills and billing scenarios, which of the following statements is correct () (multiple choice)

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