When an NCT-type option is used for NCR, the UUI is forwarded by the Avaya Communication Manager in the ISDN SETUP message sent with the call to the second site.

When the NCD option is used for NCR, the UUI is included in the ISDN FACILITY invoke message sent from the Avaya Communication Manager to the PSTN. The PSTN then forwards the UUI to the second site.

When the AT&T In-Band Transfer and Connect service is used for NCR, the UUI is returned in an ISDN DISCONNECT message that includes the data in a codeset 0 or 7 UUI IE element.