1、问题描述
00101测试卡无法注册LTE网络，modemlog中发现终端未发起Attach请求，对比正常注册非正常注册的版本，发现正常的多出了ims apn。可以通过AT+CGDCONT?来查询modem APN参数。
2、问题分析
目前Modem是一套，没有相关修改。因此需要排查上层APN 下发区别。
正常日志
06-24 15:40:45.537675 1493 1543 D RmcDcReqHandler: [0][isSupportSelfSetInitialAttach] : cardType = 2
06-24 15:40:45.537697 1493 1543 D RmcDcReqHandler: [0][isSupportSelfSetInitialAttach] : [0] of apn, supportedTypesBitmask = 512
06-24 15:40:45.537717 1493 1543 I RmcDcReqHandler: [0][handleIfVendorSelfIaNeeded] : Send EIAAPN, iaMode = 0
06-24 15:40:45.537735 1493 1543 I RmcDcReqHandler: [0][handleIfVendorSelfIaNeeded] : send EIAAPN, apn =
06-24 15:40:45.537762 1493 1520 D RfxRilAdapter: responseToRilj, request id = 128
06-24 15:40:45.537787 1493 1543 I AT : [0] AT> AT+EIAAPN=*** (RIL_CMD_READER_4, tid:512323509488)
异常日志，没有下发AT+EIAAPN
06-21 12:45:32.543734 1433 1475 D RmcDcReqHandler: [0][isSupportSelfSetInitialAttach] : cardType = 2
06-21 12:45:32.543760 1433 1475 D RmcDcReqHandler: [0][isSupportSelfSetInitialAttach] : [0] of apn, supportedTypesBitmask = 64
06-21 12:45:32.543782 1433 1475 D RmcDcReqHandler: [0][isSupportSelfSetInitialAttach] : [1] of apn, supportedTypesBitmask = 2048
06-21 12:45:32.543800 1433 1475 D RmcDcReqHandler: [0][isSupportSelfSetInitialAttach] : [2] of apn, supportedTypesBitmask = 512
06-21 12:45:32.543844 1433 1455 D RfxRilAdapter: responseToRilj, request id = 128
06-21 12:45:32.544129 2285 2556 D RILJ : [0146]< SET_DATA_PROFILE [PHONE0]
排查MTK RILD代码，当APN仅仅只有IMS 和 EMEREGENCY APN时，允许设置IA APN，否则不允许设置IA APN
异常Log中上层APN中，存在如下类型，多出XCAP APN，导致问题。
3、解决方式
方法1、删除XCAP APN
方法2、增加default 或IA APN