This attribute defines the acceptable set of screening modes. The
screening mode is carried by the Calling Party Number information
element (IE) of the B-Channel request packet. There are four types
of mode:
upns - User provided, not screened
upvp - User provided, verified and passed
upvf - User provided, verified and failed
np - Network provided
When a call is received with a screening indicator not provisioned
in the list, the call is cleared.
Description of bits:
upns(0)
upvp(1)
upvf(2)
np(3)