This interface is used by the gsmSCF to request information from the HLR (via the Any-time Interrogation function) or
to allow call independent related network- or user-initiated interaction between an MS and the gsmSCF (via the USSD
function). Support of the gsmSCF-HLR interface is a network operator option. As a network operator option, the HLR
may refuse to provide the information requested by the gsmSCF.