automatic message accounting (AMA)
Automatic Message Accounting (AMA) is the collection, recording and calculation of connection charges.
The AMA process was introduced in the 1950s with the self-dialing telephone service(SWFD) and records the call data with the call time. The billable calls are processed in the Operating Support System( OSS).
In the AMA process, there is the centralized AMA (CAMA) and the local AMA (LAMA). In the centralized AMA, the connection data is obtained in a Class 5 switch using Automatic Number Identification( ANI) and multi- frequency dialing and used to calculate the connection charges.