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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We are using Honor 7X mobile phone with Huawei Kirin modem and observed that GPRS and EGPRS attach is not working with Huawei Kirin Modem phones.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">There is no issue observed from OSMO-PCU. it seems either Huawei Kirin modem issue or OSMO-SGSN issue.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please check below analysis for this issue.<br>
<br>
<o:p></o:p></p>
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1- UE send attach request with IMSI and invalid MCC and MNC to SGSN.<o:p></o:p></p>
<p class="MsoNormal" style="font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;text-decoration-style: initial;text-decoration-color: initial;word-spacing:0px">
2- SGSN send Identity Request with IMEI to UE.<o:p></o:p></p>
<p class="MsoNormal" style="font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;text-decoration-style: initial;text-decoration-color: initial;word-spacing:0px">
3- UE responded Identity Response with IMEI to SGSN.<o:p></o:p></p>
<p class="MsoNormal" style="font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;text-decoration-style: initial;text-decoration-color: initial;word-spacing:0px">
4- SGSN sends ATTACH ACCEPT message to SGSN with new PMTSI but UE is not responding ATTACH COMPLETE message to SGSN and resend ATTACH REQUEST message to SGSN.<o:p></o:p></p>
<p class="MsoNormal" style="font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;text-decoration-style: initial;text-decoration-color: initial;word-spacing:0px">
5- SO SGSN re transmit ATTACH ACCEPT message to UE and after max number of re transmission , SGSN is release UE MM context.<o:p></o:p></p>
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<o:p></o:p></p>
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It seems that UE is not accepting ATTACH ACCEPT message.<o:p></o:p></p>
<p class="MsoNormal" style="font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;text-decoration-style: initial;text-decoration-color: initial;word-spacing:0px">
<o:p></o:p></p>
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We also observed that Huawei Kirin UE is sending wrong LLC data to SGSN.<o:p></o:p></p>
<p class="MsoNormal">UE had set more bit in RLC LME header and send invalid LLC data with 0x2B.
<o:p></o:p></p>
<p class="MsoNormal">So OSMO-PCU had forward this data to SGSN because more bit is set and SGSN
<o:p></o:p></p>
<p class="MsoNormal">is complaining LLC error for this LLC data.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please look into this issue or let us know if we have fix for this issue.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Bipin Jaiswal<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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