B13'H-B14'H, B16'H, B1A'H-B1F'H, DOO'H- D01'H, D04'H, D07'H-D08'H) In the new grouping, clean codes related to failures in the radio interface are grouped into group 6. The following is a list of CCs for group 6: 205'H: radio if congestion B13'H: radio interface failure B14'H: handover failure B16'H: remote equipment failure B1A'H: BSSMAP protocol error B1B'H: radio interface message failure BIC'H: radio interface failure reversion to old channel BID'H: O&M released inside network B1E'H: radio resource unavailable B1F'H: requested terrestrial resource unavailable DOO'H: subscriber signalling message content error D01'H: subscriber signalling message format error D04'H: subscriber signalling protocol error D07'H: no response to call establishment; alerting or connect D08'H: GSM ERH 4.08 protocol timer expires The result of the call answer rate analysis is a report on the amount of calls successfully completed by either subscriber A or subscriber B and the share of technically successful calls. As an example, Figure 4.40 presents the results of the call answer rate analysis for nine months in one MSC. These results show an increase in technically successful calls during the analysis period. Network Configuration Assessment The main objectives of network configuration assessment are: review the existing voice network topology; review the existing signalling network topology; CX_MSC January February March April August Week 34 October November December Radio Interface Errors Subscribers Errors External Congestion Internal Congestion Rest of Tech. Succ. Calls 34.8% 34.6% 35.2% 38.3% 39.4% 38.5% 40.6% 40.7% 40.4% 54.0% 54.2% 53.9% 50.5% 50.1% 53.1% 53.4% 54.0% 53.9% Answered Calls Figure 4.40 Call answer rate analysis CS Core Network Optimisation analyse the network naming convention; VLR parameter review; HLR parameter review; proposals and suggestions for improvement. 4.7.4 Audit Results Analysis The reports generated during the network audit serve as a vital input in the audit results analysis module. This module com