Synchronization specialist Visto Corporation has expanded its lawsuit against rival, and Bay Area neighbor Seven Networks. Visto says that Seven Networks infringes on four of its patents, (USPTO Numbers 6,131,116, 5,961,590, 5,968,131 and 6,708,221) all relating to synchronization between a remote device and a central server or network. Visto was granted a ninth patent (USPTO No. 6,708,221) in this area twelve days ago.

Seven Networks sells mobile email software to carriers, and boasts DoCoMo, KDDI and Orange as customers. The company includes former Microsoft luminaries Nathan Myhrvold - founder of Microsoft Research - and Brad Silverberg.

"Unfortunately, Visto is asserting more of the same old technology that in large part relates to store and forward file replication methods that require storing customer data outside of the firewall on a third party server," responded Seven in a statement. "As a security precaution, Seven's software architecture was designed to avoid the replication of corporate data on a third-party server outside the firewall."

Seven vowed to defend the suits aggressively.

Seven Networks filed for a stock offering last month, although unlike Google, it's still very much in dotcom mode, having reported a loss of $12.9m on revenues of $6.9m last year. Visto meanwhile recently acquired synchronization software developed by Psion Computer. The company raised an additional $15m in venture funding this month. ®

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