As per my knowledge in R12 some of the information is transferred to HZ_Tables.
For Example: Supplier Contact Details which is available in PO_SUPPLIER_CONTACTS in 11i while in R12 some of the supplier contact details are transferred to HZ_ tables. You have to map up the AP_SUPPLIER_CONTACTS and HZ_ tables to retrieve of supplier contacts.
Pl. review the following MOS Doc.
How to See Supplier Contact Information Using SQL in R12 (Doc ID 761456.1)