Here is an EXCLUSIVE tutorial to use any sim card Vodafone's k3570-z usb modem (METHOD 1)
It is manufactured by Zte Corporation, China. k3570-z supports 2g,EDGE,3G upto 3.6 mbps and it has no memory card slot.
Using this trick you can use other sim network's sim cards on this modem.
Basically, when you insert another operators sim in Vodafone k3570-z it does not asks you for the unlock code because I think that it is pre-unlocked.Because of the Vodafone's dashboard does not recognize aunauthorized or other networks sims card and it looks like this if you inserts other sim: