4. Some node (SGSN or SMSC) must generate CallDetailRecords about MT-SMS and MO-SMS for Postpaid bills.
5. In case if You have prepaid subscribers in Your network, You shold check IDP-messages presence from SGSN to Your SCP with information for prepaid billing.
Just another question, to check the usage of SMS encoding i ask the VAS Guy (SMSC one) and he said me that all enconding scheme are supported and that it depends on the mobile, so how determine the encoding for SMS?