[IMS Tech] Solutions available that can be used to provide features from IMS (from Application Servers in IMS Network) to Circuit Switched Domain users in a Mobile Network?

[Nadun]

Dear All

I am looking for  Solutions available that can be used to provide features from IMS (from Application Servers in IMS Network) to Circuit Switched Domain users in a Mobile Network?

If a mobile operator got an IMS core and, Hosted PABX Application server is one of its AS providing features for Broadband and PS subscribers. If the operator wants to extend this Hosted PABX feature to the normal 2G and 3G CS domain users what are the Solutions available,?
What are the Industry practices? What are the standards defined in 3GPP/3GPP2?

Nadun