Foreign-based criminals are reportedly ripping off Australian companies by hacking into their telephone systems and racking up massive bills.  Last week a Melbourne retailer and university were hit with collective phone bills for more than 100-thousand dollars of overseas calls.  And both parties are angry with Telstra which they say is insisting they pay the bills.  The Camberwell Electrics Superstore says it was contacted by Telstra to ask why it had made 20 thousand dollars worth of overseas calls in less than two weeks.  And Swinburne University says it knew nothing about the scam until it was hit with an 80-thousand dollar bill.