Section: 5.5.3.2 'Visitors' from other PLMNs
Content: The CDRs collected from the network also include details of the services employed by visiting (roaming) subscribers. The charges for Mobile Originated Calls (MOCs) and for supplementary services used are calculated as for home subscribers, converted to an agreed accounting currency and included in the CDRs for the TAP. Even if Mobile Terminated Calls (Cs) are zero-priced in the visited network (VPLMN), in the absence of 'optimized routing' the C TAP records are still required by the home network (HPLMN) in order to determine the re-routing charges from the HPLMN to the VPLMN. The TAP records generated are exchanged with each HPLMN on a regular basis. These TAP records form the basis of the invoice submitted by the VPLMN for the traffic carried.