In the past, for ISDN trunks, look-ahead interflow transported the LAI Information Element (IE) in codeset 6 or 7, which functioned over non-QSIG private networks, but only over certain public networks.
Now, call centers can transport application information (including the LAI information) over many more public ISDN networks using User to User Signaling (UUS) Supplementary Services that incorporate user-to-user information (codeset 0 UUI). Information passes over QSIG private networks using manufacturer specific information (MSI - codeset 0 Facility IE) in various messages.
User-to-user information can also be transported over SIP trunks. You can use this feature to:
