问题：

[单选] An important limitation of the Cisco Business Ready Teleworker solution is_____.（）

A . IP phone extensions for teleworkers must be chosen carefully so not to duplicate campus phone extensions.
B . More security exposure exists due to lack of support for Intrusion Detection System and URL filtering for teleworker originated traffic.
C . Compressed RTP and IPSec are not compatible and result in no bandwidth savings.
D . Broadband modems must support Quality of Service for adequate voice quality.