The following items are criteria for basic LAI call control operation over a VPN or a public switched network:

• The sending and receiving call center locations must have ISDN PRI or BRI trunk facilities.

  Note:

  ATM trunking and IP trunking can be set up to emulate ISDN PRI, but first verify that the release of Communication Manager that you have still supports the use of ATM trunking.

• The switch must support the ISDN country protocol.

• LAI has been tested with several major carriers. To find out if the capabilities work with your carrier, check with your account team for the latest information. If testing is not done to verify operation over the public networks involved with the preferred specific configuration, use private ISDN trunking between the nodes until successful testing is complete.

• The ISDN SETUP and DISCONNECT messages are transported between sending and receiving locations, for example, Signaling System 7 (SS7) or equivalent public network connectivity.

• A receiving-end generated DISCONNECT message must transmit back to the sending switch call center without changing the cause value.

  Conversion of the DISCONNECT message to a progress message, with a Progress Indicator Description set to 1 and a cause value other than 127 included, is a valid reject message and compatible with LAI.

• Progress messages that are generated towards the sending end by intervening network switches must have the Progress Indicator Description set to 8 so that the switch does not treat the call accepted or rejected.

• ISDN codeset 0 user information transport supports LAI information forwarding. As an alternative, LAI can use dedicated VDNs at the receiving location to provide an equivalent display of the forwarding application identity and set trunk group options to not send either the codeset 6/7 LAI IE or codeset 0 information transport.