SQL> create table t ( x int );

Table created.

SQL> create table t1 ( x int );

Table created.

SQL>
SQL> create or replace
  2  trigger TRG
  3  instead of insert on T
  4  for each row
  5  begin
  6    insert into t1 values (:new.x);
  7  end;
  8  /
instead of insert on T
                     *
ERROR at line 3:
ORA-25002: cannot create INSTEAD OF triggers on tables


SQL>
SQL> create or replace view V as select * from T;

View created.

SQL>
SQL> create or replace
  2  trigger TRG
  3  instead of insert on V
  4  for each row
  5  begin
  6    insert into t1 values (:new.x);
  7  end;
  8  /

Trigger created.

SQL>
SQL> insert into v values (1);

1 row created.

SQL>
SQL> select * from t;

no rows selected

SQL> select * from t1;

         X
----------
         1

1 row selected.

SQL>
SQL>