| 摘要 |
An advanced intelligent network (AIN) telephony service permits users of a dedicated access line (DAL) service to place toll free calls over the DAL, even when the long distance network cannot query a national toll free database, such as a national service management system (SMS). A switch in the long distance network, which cannot access the toll free network, receives the toll free call and forwards the toll free call to a switch that can access the national toll free database. In one embodiment, the switch that can access the national toll free database resides in a local exchange carrier (LEC) network. Thus, the DAL subscribers do not have to route toll free calls over local trunks.
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