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Transfer Account Procedure TAP

Transfer Account Procedure TAP

TAP Transfer Account Procedure:
Exchange of information required for billing and accounting purposes between GSM operators
What is TAP and how it work ?
The Transferred Account Procedure is the mechanism by which GSM operators exchange roaming billing information. This is how roaming partners are able to bill each other for the use of GSM networks and services.

In order to place a call from an INDIAN PMN to a Canadian fixed phone, it is not necessary for the INDIAN PMN operator to negotiate a price with a Canadian fixed network operator.
The INDIAN PMN operator negotiates a price with the INDIAN fixed network operator. The INDIAN fixed network operator then negotiates a price with the Canadian fixed network operator. So, the INDIAN fixed network operator passes this call cost back to the INDIAN PMN. This means that the INDIAN PMN has to recoup the cost of the call from its subscribers either directly (retail billing), or via the appropriate Service Provider (wholesale billing).
This form of inter-administration accounting covers the division of revenue between both fixed and mobile networks. It does not, however, cover the costs incurred by foreign subscribers whilst roaming in other networks.
The following figure illustrates the collection and transfer of TAP information between the Home Public Land Mobile Network (HPLMN) and the Visited Public Land Mobile Network (VPLMN)
 TAP Transfer Account Procedure
The details of the calls made by a subscriber roaming in a visited network (VPLMN) are recorded by the serving switch MSC. Each call produces one or more call records CDR. The call records produced by the MSC are transferred on a regular basis to the billing system of the VPLMN for rating. Those call records produced on behalf of roaming subscribers, will be converted and grouped in files under the TAP format. The TAP files are generated and sent, at the latest, 36 hours from call end time. This means that operators can send 1 or many TAP files per day. TAP files contain rated call information according to the operator's Inter Operator Tariff (IOT), plus any bilaterally agreed arrangements.
On reception of TAP by the HPMN, the TAP record is converted into an internal format and added together with any call records produced by the subscriber whilst within the home network.
If a service provider serves the subscriber then the records will form the basis of the wholesale billing between the HPMN and that Service Provider. On receipt of the information from the HPMN, the Service Provider may re-rate the calls according to its own tariff plans and produce an itemised bill.
TAP3 is the new version being used by operators which supports a variety of mobile services and those currently in use are outlined below.

·         Roaming Scenarios

·         GSM Basic Services

·         SMS - Short Message Service

·         Data

·         Value Added Services (VAS)

·         CAMEL

·         Inter Operator Tariff (IOT) Charging Principles

·         Marketing and Customer Service

·         Rejects & Returns Process

The Returned Accounts Procedure (RAP) was introduced on 1st April 2001 and is supported by TAP3.
In some cases individual erroneous call event details are rejected, resulting in loss of revenue to operators. The rejects and returns procedure deals with this by introducing a new automated, standardised method for handling erroneous TAP files.
The Rejects and Returns process enables operators to:
• Maximise the collection of revenue for both Home Networks and Visited Networks
• Deliver fewer call event details in the reclaims process, making for a simpler invoicing process, which may facilitate future net settlement requirements
• Support non-standard validation checks which may have been agreed bilaterally between roaming partners


The VPLMN Operator shall make data in respect of roamed calls available to the HPLMN Operator (or the HPLMN Operator's agent) through the TAP within 72 hours (until 31st August 1998)and then 36 hours from 1st September 1998 of the call end time. This shall be the "Standard Timescale" for the transfer of data and is a reasonable period of time for the collection and processing of data from remote switches.
Each TAP transfer should include all charging records that are available at the time of transmission including partial charging records.
PLMN Operators should ensure that the transfer of charging records more than 72 hours old is truly exceptional.
The data made available are considered as being valid unless the HPLMN Operator notifies the VPLMN Operator without delay, in writing, of a problem with the file or the data.