Hi mac…
well m a bit confused, as the error causes that you had mentioned (FAIL_GPRS_Attach_Due_SGSN_ERR & FAIL_GPRS_Attach_HLR_VLR_ERR) are purely core end and protocol related issues, so how come changing initial coding schemes improved the attach success rate? did u see improvement in VLR and SGSN errors as well or they are intact…???
waiting for your response..