与RNC配合问题导致呼叫失败..doc

与RNC配合问题导致呼叫失败 一、问题描述： H省某型号手机主叫失败。原因是由于主叫和被叫的承载能力协商不一致，然后华为软交换给主叫RNC下发了二次指配，主叫RNC直接拆线。该RNC是友商Z公司设备，Z公司认为协议上没有强行规定一定要二次指配为编码交集，相关消息为可选消息。因此要求华为软交换修改。 二、相关告警： 无相关告警信息。 三、问题分析： 1、分析呼叫信令。主叫SETUP消息中，手机上报其支持两种codec，分别为AMR和AMR2，如下图： 对于supported codecs的解释，协议定义如下： 10.5.4.32 Supported codec list The purpose of the Supported Codec List information element is to provide the network with information about the speech codecs supported by the mobile. The Supported Codec List information element is coded as shown in figure 10.5.118c/3GPP TS 24.008. The Supported Codec List information element is a type 4 information element with a minimum length of 5 octets and a maximum length of m+3 octets. Speech codec information belonging to GSM and UMTS radio access shall be conveyed by this information element. 8 7 6 5 4 3 2 1 Supported Codec List IEI octet 1 Length Of Supported Codec list octet 2 System Identification 1 (SysID 1) octet 3 Length Of Bitmap for SysID 1 octet 4 Codec Bitmap for SysID 1, bits 1 to 8 octet 5 Codec Bitmap for SysID 1, bits 9 to 16 octet 6 System Identification 2 (SysID 2) octet j Length Of Bitmap for (SysID 2) octet j+1 Codec Bitmap for (SysID 2), bits 1 to 8 octet j+2 Codec Bitmap for (SysID 2), bits 9 to 16 octet j+3 System Identification x (SysID x) octet m Length Of Bitmap for (SysID x) octet m+1 Codec Bitmap for (SysID x), bits 1 to 8 octet m+2 Codec Bitmap for (SysID x), bits 9 to 16 octet m+3 Figure 10.5.118c/3GPP TS 24.008 Supported codec list information element Table 10.5.4.135c/3GPP TS 24.008: Supported Codec List information element Octet 3, (j+1), m etc SysID indicates the radio access technology for which the proceeding codec types may be used. Coding of this Octet is defined in 3GPP TS 26.103. Octet 4, (j+2), m+1 etc Length Of Codec Bitmap for SysID indicates the number of octets included in the list for the given SysID. Octets (5 6), (J+2 j+3), (m+2 m+3) etc The coding of the Codec Bitmap is defined in 3GPP