Customers of consumer VoIP provider ooma lost service for about six hours Monday, but according to ooma, irate users should point the finger at Internap instead. Dennis Peng, vice president of product management for ooma, wrote in a blog post that all ooma customers were affected by the outage and that upstream Internet service provider Internap was the source of the connectivity issues.

Internap didn’t waste time firing back at ooma, as spokeswoman Debra Forrester said the problem was not Internap’s fault, and that no other Internap customers experienced a connection failure, indicating the problem was within ooma’s system, not Internap’s.

Ooma Chief Marketing Officer Rich Buchanan wrote an email saying ooma had network logs to prove the disruption was due to an issue with Internap’s systems. Ooma representatives said the outage has prompted them to expedite plans to launch a second data center in the U.S. for emergency failover capabilities.