Advice of Charge

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With Advice of Charge ( AOC ) is in the telephone network , the transmission of charge information refers to the subscriber. This is possible with both ISDN and cellular connections. A distinction is made between several variants of this performance feature.

variants

AOC-D

The AOC-D feature describes the transmission of tariff information during a connection ( AOC During the call ).

This is at an ISDN terminal , the display of incurred so far in an existing call connection costs possible. In the case of analog telephone connections , the tariff unit is transmitted by means of a charge pulse . With ISDN connections, the information is transmitted in the D channel .

AOC-E

The AOC-E feature describes the transmission of tariff information after a connection has been terminated ( AOC at the end of the call ).

This means that the connection costs incurred can be displayed on an ISDN terminal after the connection has been terminated. AOC-E only works with ISDN connections. Analog telephone connections cannot use this feature.

AOC-S

The AOC-S feature describes the transmission of tariff information before and, if necessary, during a connection ( AOC at call set-up time ).

AOC-S offers much more detailed tariff information than AOC-D and AOC-E. At the beginning of the connection, information about the estimated costs is communicated to the ISDN terminal. For this purpose, the exchange transmits the multiplier per tariff unit, as well as the value for the duration per tariff unit. The multiplier as well as the duration can vary during a connection. This enables variable tariffs for connection charges to be displayed correctly. This feature is currently only offered by a few network operators. In addition, the transmission of AOC-S is only evaluated by some telephone systems and public telephones ( coin-operated telephones ). The latter can use it to check whether enough money has been prepaid for this connection.

General

With the AOC features, the connection costs are usually not transmitted directly, but as so-called tariff units. These units must be multiplied by the end device before the display with a currency factor permanently entered in the end device. The transmission of amounts of money is provided for in the standardization, but is not yet supported by the network operators . There may be discrepancies between the costs shown and the costs calculated. Because:

  • The tariff structures of the various network operators are variable and often cannot be fully mapped onto the tariff unit model.
  • The generation of the AOC information is usually independent of and not linked to the "billing system", the computer that carries out the calculation for invoicing.

standardization

For the telephone network, AOC for ISDN is specified in the ITU -T standard Q.956.2 and in the ETSI -TS 300178 to 300182.

For cellular networks , the standards for GSM are described in ETSI- ETS 300395 and ETSI -EN 300395, for UMTS the standards are described in ETSI -TS 123086.

For the TISPAN NGN Release 2 there is the ETSI TS 183047 standard, which was adopted by 3GPP for the IMS under 3GPP TS 24.647.

There are other similar standards for AOC in other national / international standardization bodies.

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