Can anyone tell how CRM Transactions are saved by sap

My question is when i save any sales document say quotatin how the data is saved by sap.Do they use a bapi or crm_order_mainatain or something else ?IF they use how do u guys debug to reach that place?Kindly help.

Please also tell the name of bapi .Please also tell how to debug to that place or hwo do u knw it??