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Reply To: SD Drop Rate after MSC shifting


it sounds like there is a misconfig in the MSC.

the SDCCH drop is caused by the expiry of a timer during the sdcch phase. The sdcch phase is a dialog between MS and MSC : authentication, ciphering, call setup, equipment check (= DTAP messages).

Timer expiry is normally caused by a radio failure, but in your case it might be due to a non-response from MSC or from MS.

Have you performed a A trace to detect when is the failure occuring ?