Syncing while aboard using WiFi

Hello crackberry nation.

I have this problem, when I travel to other countries where roaming :mad: charges are so high I have a local prepaid SIM. The problem is that when I swap sims I no longer have Blackberry service (It's a prepaid sim for local & international calls) but when I load the WiFi service I can't sync my blackberry either. I'm using both BES for corporate mail & BIS for personal mail.

Any ideas on how I can use WiFi to synchroniza my blackberry wireless or do I have to get a SIM card with blackberry service in it.

FYI Corporate mail works great on the companys WiFi solution but over open internet I can't sync any mails